Lost keys • controlled replacement • incident-safe options

Replace Lost Keys in an Existing Suite

Lost keys don’t have to become a site-wide panic event. The right response depends on which tier was lost (CK vs master tiers), whether it was identifiable, and how well the suite is documented. We help you choose a controlled replacement route-fast when needed, safe always.

Risk-based response Works with legacy suites Emergency options available
Emergency rekeying Get a quote Lost master key guidance
Back to Master Key Systems or browse High-Intent pages.
Fast triage checklist
  • Which tier was lost? (CK / SMK / MK / GMK)
  • Was it labelled or with ID/address info?
  • Is access currently blocked?
  • Do you have any remaining keys from the same tier?
Key control policies • Hierarchy explained
Quick contact
Emergency rekeying 24/48h options Call us 01296 752080 Email incident details info@lockandkey.co.uk Expand / stabilise a suite
Real premises, real support team
About us

Trusted master key system support

Speak to an MLA accredited locksmith team with in-house planning, documented suite records, and practical support before and after installation.

MLA Accredited
Aylesbury HQ
Online system management
Master Locksmiths Association BSI Kitemark

Master locksmiths with BSI accreditation

MLA approved locksmiths, BSI certified key systems, and independently audited security standards.

Customer reviews
reviews
4.8 out of 5
19,000+ reviews on Trustpilot
Why we left Trustpilot
1 hour ago

Easy to navigate website and ordering if you have the information required. Packed well and fast delivery. 1st class service. Highly recommend this company.

Sandra Thorn
Read reviews on Google

What kind of key was lost?

Different tiers require different responses. The fastest “safe” fix is the one that matches the real risk.

Lost a change key (CK)

Often low impact, but context matters: was it labelled, on an ID lanyard, or linked to a known door?

Typical response
Risk assess, then replace keys and review whether the door should be rekeyed.
Key control policies Hierarchy explained

Lost a sub-master / master key (SMK/MK)

Medium-high impact. These tiers can open multiple doors and can escalate risk quickly.

Typical response
Treat as an incident: identify tier, affected doors, and decide whether selective rekey or controlled replacement is safest.
Lost master key guidance Emergency rekeying

Lost a grand master key (GMK)

High impact. A GMK can expose the entire suite depending on design.

Typical response
Immediate escalation: consider emergency rekeying, tier redesign, or controlled replacement.
Emergency rekeying High-security systems

Restricted / patented keys

Replacing is straightforward when ordering is controlled and the suite is documented.

Typical response
Confirm authorisation route and system references, then cut and supply against the plan.
Restricted key systems Key control policies

Lost keys in an HMO?

HMOs tend to have higher churn and higher copying risk. The safest fix depends on tier and exposure, not guesswork.

HMO key control guidance

What we need to replace keys safely

If you don’t have full details, that’s fine. Photos of keys and cylinders usually gets us moving quickly. The key is to avoid “guessing” in a way that creates future conflicts in the suite.

What was lost
CK / SMK / MK / GMK, and how many keys.
Where it was lost
On-site/off-site, labelled/unlabelled, with ID or address information.
What you have now
Any remaining keys from the same tier; photos help.
Timeline
Is this urgent / operationally blocking access?
System details
Brand/profile if known, or send photos and we’ll advise.
Emergency rekeying Key control policies Restricted keys

When replacement becomes rekeying

Sometimes the safest option isn’t “cut another key”. It’s selective rekeying or stabilising the suite:

Lost key was labelled or tied to an address

Higher risk. You may need selective rekey for exposed doors.

Master tier key lost (SMK/MK/GMK)

Treat as an incident. Emergency options may be appropriate.

Suite is undocumented or drifting

Audit-first prevents breaking the suite during “fixes”.

Related guidance
How to replace a lost master key Audit outdated or unknown suites Expand an existing master key suite Mechanical vs electronic hybrid systems
Expand an existing system Convert to a master key system

Lost keys by industry

Sector pages include common incidents and typical response patterns in each environment.

View all industries

Hospitals & NHS Estates

Trigger events, hierarchy examples, and key control processes under real operational pressure.

Local Authorities

Trigger events, hierarchy examples, and key control processes under real operational pressure.

Schools & Colleges

Trigger events, hierarchy examples, and key control processes under real operational pressure.

Universities

Trigger events, hierarchy examples, and key control processes under real operational pressure.

Build-to-Rent (BTR)

Trigger events, hierarchy examples, and key control processes under real operational pressure.

Housing Associations

Trigger events, hierarchy examples, and key control processes under real operational pressure.

Facilities Management Companies

Trigger events, hierarchy examples, and key control processes under real operational pressure.

Commercial Buildings

Trigger events, hierarchy examples, and key control processes under real operational pressure.

Replacing lost keys: common questions

Open the sections you need.

Can you replace keys if we don’t know the brand or profile? ⌄
Often yes. Send photos of the keys and cylinders and we’ll advise the safest route. If the suite is unknown or drifting, an audit-first approach is usually best.
Audit unknown suites
Do we have to rekey doors when a key is lost? ⌄
Not always. It depends on the tier and exposure. A lost change key may be low risk; a lost master tier key is usually higher risk. We’ll recommend the least disruptive option that restores control.
What’s the fastest safe option for master tier loss? ⌄
Escalate quickly, confirm tier and exposure, then decide between selective rekey and emergency rekeying based on operational risk and time pressure.
Lost master key • Emergency rekeying

Need lost keys replaced safely and quickly?

Tell us what tier was lost and whether it was identifiable. We’ll recommend the safest response and arrange replacement, selective rekeying, or emergency rekeying.

Emergency rekeying Get a quote Key control policies

Prefer to talk?

Phone: 01296 752080
Email: info@lockandkey.co.uk

Also planning work? Expand your existing system
Online management included

See how your whole system connects

Explore your keys, groups and communal doors in a visual system map. See expected access connections, give people the keys they need, and manage orders and permissions in one secure place.

People & permissionsNormal or management access, selected keys and date windows.
Restricted-order approvalsCheck the requester, delivery address and exact keys before deciding.
Complete order historySee every restricted order linked to the system in one place.
Timeline & documentsKeep customer-visible records separate from protected system charts.
Explore the interactive demo Open your systems
Your system, mapped out TSR123 · Example
MASMaster key
Group A
SMA · Sub-master
A1 A2
COMACommunal
Group B
SMB · Sub-master
B1 B2
COMBCommunal
Group C
SMC · Sub-master
C1 C2
COMCCommunal
Group D
SMD · Sub-master
D1 D2
COMDCommunal
Follow the groups. Find the shared doors. Explore expected key access.
Try the system map
Orders & approvals Owner view
Example owner decision: an unauthorised request is reviewed, denied and recorded. No real orders are shown.
Restricted-order approvals

You decide who gets the keys.

An order outside someone’s access comes to you for approval. Check who is ordering, where the keys are going and exactly what they requested. Approve it when it checks out, or deny it when it doesn’t.

Pair these approvals with PREM 4, our usual patented keyway, for control over key supply as well as who can order. Every decision leaves a record in your system’s history.

Try an example key order Order TSR / HMJ keys

Already have TSR or HMJ keys? Use the ordering page above. For another key range, contact us to find the matching product.