The Best MDR for Microsoft 365
The best MDR for Microsoft 365 in the UK combines identity-first detection across Entra ID sign-in risk and conditional access, native use of the Microsoft Sentinel and Defender licences you already own, business-email-compromise and inbox-rule detection, and a UK SOC with the authority to revoke sessions and disable accounts against a committed human response time. This guide compares 7 providers: Precursor Security, Bridewell, Quorum Cyber, Sophos MDR, Red Canary, Huntress, and e2e-assure, on criteria any buyer can check independently.
Seven managed detection and response providers compared specifically on Microsoft 365: whether detection is identity-first rather than endpoint-only, whether monitoring is Sentinel and Defender-native, and whether incident response and session-revocation authority are included.
We are Precursor Security, and we have ranked ourselves first on this list.
Rather than pretend otherwise, we publish the selection criteria in full, describe every provider fairly, and mark where each one is headquartered and owned so you can weigh it yourself. Two of the seven are US-headquartered and one has changed ownership within the last year, all clearly labelled, because ownership and SOC location are among the things this guide compares. The firms below are genuinely capable at what they do; the differences are in identity-detection depth, transparency, and who each serves best. Confirm any CREST claim in the independent CREST member directory.
Seven providers, side by side
| Provider | HQ / ownership | SOC region | Pricing published | From |
|---|---|---|---|---|
| 1. Precursor Security | UK (Newcastle) | UK, physical | Yes | From £900/mo |
| 2. Bridewell | UK (Reading) | UK | No | On application |
| 3. Quorum Cyber | UK (Edinburgh) | UK | No | On application |
| 4. Sophos MDR | UK (Thoma Bravo-owned) | UK / global | No | On application |
| 5. Red Canary | US (Zscaler-owned) | US / global | No | On application |
| 6. Huntress | US | US / global | No | On application |
| 7. e2e-assure | UK | UK | No | On application |
Verified against each provider's public website and public corporate records, September 2026. "No" under pricing means a rate was not published at the time of writing, not that a provider is more expensive. Ownership reflects public records: Sophos is owned by Thoma Bravo; Red Canary is owned by Zscaler following its August 2025 acquisition.
The 7 best MDR providers
for Microsoft 365 in 2026
1. Precursor Security
Precursor runs a physical, CREST-accredited SOC in Newcastle with UK-based, DBS-checked analysts and no offshoring. Monitoring is Microsoft Sentinel-native, correlating Microsoft Defender alerts, Entra ID sign-in and conditional-access risk events, and the M365 Unified Audit Log across Exchange Online, SharePoint, OneDrive, and Teams, rather than bolting on a separate agent stack. Pricing starts from £900 per month, published on the website, with fixed monthly quotes after a free scoping call. Critical alerts, confirmed BEC, account compromise, or active exfiltration, get human analyst investigation within 10 minutes of firing, 24/7/365, with a named contact for escalation. Full incident response, including session revocation, account disablement, and OAuth grant removal, is included with no separate retainer, monitoring is vendor-agnostic rather than locked to one platform, and the closed-loop model means penetration testing of the same tenant feeds directly into detection rules.
Trade-off: A UK mid-market specialist rather than a global enterprise brand, with a smaller analyst pool than the largest providers on this list.
2. Bridewell
Bridewell is a UK-headquartered consultancy based in Reading with one of the most heavily accredited Microsoft practices among UK providers: a Microsoft Security Solutions Partner, Security and Sentinel Elite Partner, and a member of the Microsoft Intelligent Security Association (MISA), running a Microsoft-verified managed XDR service built on Sentinel and Defender. For an organisation that wants Microsoft accreditation depth alongside monitoring, it is a strong shortlist candidate.
Trade-off: A larger consultancy engagement model that can feel weighty for a smaller mid-market requirement. Pricing is on application.
3. Quorum Cyber
Quorum Cyber is a UK-headquartered provider based in Edinburgh that publicly describes itself as a Microsoft-first cybersecurity specialist, building its managed detection service around Microsoft Sentinel and Defender rather than a multi-vendor stack. For an organisation already committed entirely to the Microsoft security suite, that focus is the appeal.
Trade-off: A Microsoft-only specialism, which is a strength if your estate is entirely Microsoft and a limitation if you run other SIEM or EDR tooling alongside it. Pricing is on application.
4. Sophos MDR
Sophos MDR is operated from the UK but sits inside a US private-equity-owned group: Sophos was taken private by Thoma Bravo in 2020 and later acquired Secureworks and its Taegis platform in 2025. For a buyer wanting Sophos endpoint and firewall products paired with managed detection under one vendor, the portfolio breadth is the draw.
Trade-off: Ownership sits with a US private equity firm rather than in the UK, and M365 monitoring depth beyond endpoint telemetry is worth confirming directly. Pricing is on application.
5. Red Canary
Red Canary built its reputation as a US-based MDR specialist with strong Microsoft ecosystem coverage, and was acquired by Zscaler in a deal that closed in August 2025, now operating as a Zscaler business unit. For a buyer already invested in Zscaler, the combination is worth evaluating; for a UK buyer prioritising a UK-based SOC, it is worth asking directly where the analysts investigating your tenant now sit post-acquisition.
Trade-off: US-headquartered and mid-integration into Zscaler following the 2025 acquisition; confirm current UK data-residency and support-hours arrangements directly. Pricing is on application.
6. Huntress
Huntress is a US-headquartered provider built for the SMB market, offering a Managed ITDR (identity threat detection and response) service alongside its core MDR that extends coverage into cloud and Microsoft 365 identity signals. For a smaller organisation wanting an approachable, identity-aware starting point, it is a widely used option.
Trade-off: Built for the SMB segment with a lighter-touch engagement model; larger or more complex M365 tenants may want deeper native Sentinel and Defender correlation. Pricing is on application.
7. e2e-assure
e2e-assure is a UK-headquartered managed SOC and MDR specialist that runs its own detection platform and emphasises UK-based delivery and threat hunting. It does not publicly detail Microsoft 365-specific monitoring capability beyond general MDR coverage, so ask directly how deep its Entra ID and mailbox-rule detection goes if M365 is your primary concern.
Trade-off: A general MDR and SOC specialist rather than a Microsoft-focused one; M365 depth should be confirmed directly. Pricing is on application.
How we ranked them for M365
Six criteria specific to Microsoft 365, each something a buyer should care about and can verify without taking anyone's word for it. Weighting is ours; the underlying facts are checkable.
Entra ID sign-in risk, token theft, MFA fatigue, and conditional-access gaps. The modern M365 breach path starts with a compromised sign-in, not a malware file, so a provider watching endpoints alone misses it.
Whether the provider monitors the Microsoft Defender and Sentinel licences you already pay for under E5 or Business Premium, rather than requiring a separate agent stack you must deploy and pay for again.
Whether the provider specifically detects business-email-compromise indicators, inbox rule manipulation, display name spoofing, and unusual send-volume patterns, not just generic phishing filtering.
Where your tenant telemetry is monitored and stored, and where the analysts investigating it physically sit. This matters for GDPR and for who is accountable when something goes wrong.
The committed time for a human to investigate a critical alert, and whether the provider can actually revoke sessions and disable accounts, not just forward an alert to your inbox. Pair this with a tested closed-loop relationship where testing and detection inform each other.
Whether the provider also runs Microsoft 365 penetration testing against the same tenant it monitors, so detection is validated against real attack techniques rather than assumed to work.
Red flags when choosing
MDR for Microsoft 365
Whichever provider you choose, including us, walk away if you see these.
Endpoint-only MDR blind to identity and mailbox rules
Ask directly whether Entra ID sign-in events and M365 Unified Audit Log activity are correlated alongside endpoint telemetry. A provider watching devices alone will not see an inbox rule created to hide a BEC conversation.
A provider that ignores the licences you already own
If onboarding requires replacing the E5 or Business Premium Defender and Sentinel coverage you already pay for with the provider's own stack, factor that added cost and disruption in before signing.
Alert forwarding with no session-revocation authority
Ask what a human analyst actually does when a critical alert fires, and whether they can revoke a session or disable an account directly, or whether it stops at an email to your inbox.
No BEC playbooks
Business email compromise is the most financially damaging M365 threat. Ask the provider to describe, specifically, how it detects inbox rule manipulation and display-name spoofing, not a generic answer about phishing filtering.
Offshore access to tenant data
Ask where the analysts who can read your Exchange and SharePoint data physically sit, and ask for confirmation in writing, not just a UK sales office or phone number.
Incident response excluded from the monthly fee
If containing a confirmed account compromise activates a second contract mid-incident, you discover the cost at the worst possible moment. Confirm whether full IR, including account containment, is included.
MDR for Microsoft 365 prices in 2026
Most providers price on application. Precursor publishes an entry price of £900 per month, scaling with tenant size and monitoring scope, with full incident response included and fixed monthly pricing after a free scoping call.
Full SOC cost guide with worked examplesResearching MDR for Microsoft 365? These guides go deeper on the services, testing, and the closed-loop model referenced above.
Compare our M365 monitoring against anyone on this list.
Sentinel-native monitoring of Defender, Entra ID, and M365 logs from a UK SOC in Newcastle. Human investigation of critical alerts within 10 minutes, with full incident response included.
Choosing MDR for Microsoft 365
The questions buyers ask most when comparing providers for their M365 tenant.
Defender for Office 365 generates alerts, but tooling without 24/7 humans investigating it leaves those alerts unworked. Defender flags a suspicious sign-in or a phishing email; MDR is the analyst who triages it at 3am, confirms whether it is a real compromise, and acts, revoking a session, disabling an account, or purging a phishing email tenant-wide, before Finance transfers funds against a fraudulent invoice. Most organisations keep Defender and Sentinel as the licences they already pay for and outsource the 24/7 investigation layer on top.
A proper Microsoft 365 MDR service correlates several signal sources rather than watching one dashboard: Entra ID sign-in risk and conditional-access events (impossible travel, MFA fatigue, legacy authentication), Defender for Office 365 alerts, the M365 Unified Audit Log for inbox-rule and mailbox changes, DLP policy violations across Exchange, SharePoint, and OneDrive, OAuth app consent grants, and Microsoft Teams activity. Identity is the layer buyers most often overlook: most modern M365 breaches start with a compromised sign-in, not a malware file.
Pricing starts from around £900 per month for a smaller M365 tenant, scaling with user count, log volume, and service tier. Precursor publishes this £900 per month entry price and gives fixed monthly pricing after a free scoping call; most other providers price on application after a sales process. Check whether incident response, including session revocation and account containment, is included in that monthly fee or billed separately as a retainer.
Yes, if the provider is Sentinel and Defender-native. A well-built M365 MDR service monitors the Microsoft Defender, Entra ID, and Sentinel telemetry you already generate under an E5 or Business Premium licence rather than requiring you to deploy and pay for a separate detection stack. Be wary of a provider that ignores the licences you already own and sells you its own agent instead; that is added cost and complexity for coverage you likely already have.
UK buyers typically shortlist a mix of UK-headquartered specialists and larger global providers. This guide compares seven serving the UK market: Precursor Security, Bridewell, Quorum Cyber, Sophos MDR, Red Canary, Huntress, and e2e-assure. The right choice depends on whether detection is identity-first rather than endpoint-only, whether the provider is Sentinel and Defender-native, whether incident response is included, and where the analysts investigating your tenant physically sit.