Brent landlords: what happens if your gas safety certificate has expired.

About a quarter of the calls I get from Brent landlords go something like this: "Jamil — letter from my managing agent, says my CP12 ran out three weeks ago, can you come tomorrow?" Yes I can. But the more interesting question is: what was actually on the line during those three weeks?

This guide is for Brent landlords with one rental or fifteen. It explains the regulation in plain English, walks through what an inspection covers, lists the real prices in HA0, HA9 and NW10, and gives you the three-step plan if you've already lapsed.

What is a CP12 — and why does it matter?

The CP12 is shorthand for the Landlord's Gas Safety Record (LGSR) — the legally-required annual inspection of every gas appliance, flue and gas pipework in a rented property, signed off by a Gas Safe registered engineer. The "CP12" name is a hold-over from the old British Gas form number; the certificate itself is officially the LGSR, but every landlord, agent and engineer still calls it a CP12.

It is required by the Gas Safety (Installation and Use) Regulations 1998, specifically Regulation 36. The rule is simple: every gas appliance, every flue, and all relevant pipework must be safety-checked annually, and a copy of the record must be given to:

• The existing tenant within 28 days of the inspection.
• Every new tenant before they move in.
• Yourself, kept on file for at least two years.

What does an engineer actually check?

A proper CP12 is not a five-minute box-tick. The Regulations specify three things must be inspected, and a good engineer will spend longer than the legal minimum on each.

1. Every gas appliance

That means your combi boiler, your gas hob, your gas fire, your back boiler, your gas oven — anything that burns gas. For each one I check: gas tightness (a 2-minute let-by/standing-pressure test at the meter), operating pressure (with a manometer at the test point), combustion (with a flue gas analyser — the FGA reads carbon monoxide and CO/CO₂ ratio), and the integrity of any safety devices like flame supervision and overheat thermostats.

2. The flue and ventilation

For combi boilers, that means a visual check of the entire flue run from boiler to terminal, including any joints in the loft or behind boxing. For room-sealed appliances in older properties, ventilation grilles and the path between them. For any open-flued appliance (rare now, mostly back boilers behind gas fires), a spillage test — holding a smoke match at the draught diverter while the appliance runs.

3. Gas pipework

The visible runs of gas pipe from meter to appliance — checking for corrosion, kinks, recent works, and that any solenoid/emergency control valve is accessible and operates.

What it should cost in Wembley

Be wary of any quote significantly under £55 in Wembley — at that price, the engineer is either skipping the flue gas analyser test (the part that catches dangerous combustion) or banking on selling you a "repair" they've fabricated. Either way, you don't want them in your tenant's living room.

The three things to do tonight if you've lapsed

Step 1 — Book the inspection NOW, not tomorrow

The fastest way to limit your exposure is to demonstrate intent. Pick up the phone — a phone call with a timestamp is a much better audit trail than a half-sent email. Most local Gas Safe engineers in Brent can fit you in within 48 hours; mine is usually same-day or next-day.

Step 2 — Notify your tenant in writing

A short, friendly email that says: "As your landlord I'm legally required to arrange an annual gas safety inspection. I've booked Jamil at Wembley Boiler Repair for [date], [time window]. Please let me know if this is inconvenient." Keep a copy. If the tenant later refuses access, this is your audit trail.

Step 3 — Notify your insurer

Most landlord policies require notification of any compliance lapse, and most are surprisingly reasonable about it as long as you flag it before there's a claim. Five-minute call. Done.

How to spot a dodgy CP12

I've seen plenty of certificates from previous engineers when I take over a portfolio. The bad ones tend to share four characteristics:

• No serial numbers on the appliances. The Regulations require the make, model and (where visible) serial number of every appliance to be recorded. A row of blanks means the engineer didn't open the casing.
• Identical CO/CO₂ readings on every appliance. No two real-world boilers produce exactly the same flue gas reading. If three appliances all report "CO 0 ppm / CO₂ 8.5%" the FGA wasn't used.
• "Visual only" ticked on the flue check, with no qualifying reason. A visual-only flue check is acceptable in some older buildings where access to the flue run is genuinely impossible — but the engineer must document why and recommend a flue camera inspection at the next service.
• No engineer signature, just a printed name. A wet signature or a verified digital signature is required.

The honest answer to the most common landlord question

The question I get asked, more than any other, by Brent landlords:

"Jamil, the tenant just emailed and said the boiler's making a noise. The CP12 was done six months ago. Am I covered?"

Mostly, yes. A CP12 is an annual safety check, not a service. It confirms the appliance was safe to use on that date. It does not warrant the appliance against breakdown for the next 364 days. If your tenant's boiler develops a fault, that's a separate repair issue — but the CP12 will be your evidence that the appliance was sound when the lease started, which matters legally and insurance-wise.

Frequently asked questions

Written by Jamil — Gas Safe registered engineer (Reg. 930067), based in Wembley HA9. CP12 inspections across HA0, HA1, HA3, HA9, NW9 and NW10. Last updated 9 May 2026. This article is general guidance and not a substitute for legal advice on specific tenancy disputes.