Lost your house keys? Here's exactly what to do, in order.

In order, before you do anything else: one, phone the people who hold your spare (a neighbour, a parent, a partner at work). Two, write a timeline of the last 30 minutes on a notepad and phone the places on that list (gym, pub, supermarket, taxi firm) where keys most often turn up. Three, only then phone a locksmith. The honest first-question I ask on the phone is "have you tried the spare-key holder yet?" because a five-minute call to a neighbour saves you paying £90 for non-destructive entry, and I would rather you save the money. If you cannot get in and cannot get the spare, I can usually pick a standard uPVC cylinder open without drilling for the non-destructive entry charge alone (from £90, no call-out fee added on top), and you decide afterwards whether you want the cylinder replaced.

Not in every case, and most national locksmith numbers will not tell you that. The honest answer depends on whether the lost keys can be linked back to your address. If the keys had no address fob, no Apple AirTag your phone can see, and you lost them somewhere unrelated to your daily routine (a gym, a pub a few miles away, a holiday town), a lock change is overkill. The keys will almost certainly end up in a lost-and-found box or a council bin lorry, useless to anyone who finds them. If the keys had an address fob, an AirTag, or were dropped on the school run or your regular commute, change the front door cylinder. That is the realistic threat, and a single cylinder change is from £90 and takes 20 minutes.

Some home-insurance policies include cover for lost or stolen keys, but in most single-key cases the excess is more than the locksmith bill, which makes claiming uneconomic. Cover amounts, excess levels, evidence requirements and reporting rules all vary by insurer, so check your policy schedule before claiming. As a rough guide on my rates: a single uPVC cylinder change is from £90, so a typical home-insurance excess of £100 to £150 would already exceed it. A four-door change after a theft is more often worth claiming on. Almost never worth claiming on a single set of "left them at the gym" keys.

For a single uPVC front door cylinder (the most common ask), from £90 standard hours, parts included for a basic cylinder. For a TS007 3-star anti-snap upgrade (the cylinder independently tested under TS007 to resist the snap attack), the labour is the same and the parts are itemised separately, usually adding £40 to £80 depending on brand. For an out-of-hours emergency, from £170. If you only need to get back into the house without changing the lock (because the keys are coming back tomorrow), non-destructive entry only is from £90. I quote the all-in figure on the phone after you describe the door, so you know what it will cost before I arrive.

On a UK uPVC or composite door, the answer is almost always replace, because the standard euro cylinder is designed as a sealed unit that is faster and cheaper to swap out than to re-pin in place. Re-pinning a cylinder takes me 30 to 40 minutes on the van, and a like-for-like replacement cylinder is £15 to £30 retail. The arithmetic only goes the other way on high-value cylinders (Mul-T-Lock, ABS, Yale Platinum) where the cylinder itself is £80-plus, in which case re-pinning the existing cylinder makes sense. On a timber door with a 5-lever BS3621 mortice lock, the lock body is usually rekeyed rather than replaced because the lock body is the expensive part. I will tell you which it is on the phone.

In most cases, yes, without damage and without replacing the lock. Standard uPVC cylinders, brass Yale-style night latches, and most mortice deadlocks open non-destructively to a skilled hand with picks or a bypass tool. Non-destructive entry only, with no new lock fitted, is from £90. High-security cylinders (TS007 3-star, anti-bump, anti-pick rated) sometimes need destructive entry where the cylinder is drilled out and replaced, and I tell you on the phone whether yours is in that category before I leave the van. Either way, you know the all-in price before I arrive, and the figure on the card machine matches the figure I said on the phone.

Change the front door cylinder, today if possible. That is the one scenario where the "change all your locks" advice is genuinely right, because someone who finds the keys and reads the fob now has both a working key and a destination. A single front door cylinder change is from £90 and takes 20 minutes. You do not need to change the back door cylinder, the window locks, or any internal locks, because they share no keyway with the front. Per the Master Locksmiths Association, an MLA-licensed locksmith can also cut a new key for the existing lock without the original if you decide later that you want to keep the cylinder.