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ADR / Evidence, claims and footage / Overwriting, and why the timing rules it

Investigations & evidence · getting the loop halted short of your clip

Overwritten CCTV footage, London. It is overwriting itself as you read this. A switch on the wall ends that.

Take it off at the wall. Ten seconds, nothing to pay, and today it outranks everything else you might do. No delete happened here and no bin holds your clip: the disk fills, the recorder goes back to block one, fresh video lands on the old, and it goes round again for as long as power reaches it. Nobody at a distance can tell you how much time is left — a figure given down the telephone is a figure given without sight of the system. But stopping the clock is yours to do, and you can do it before you ring.

No fee at all on most jobs if the files do not return Handled as an exhibit from the moment it arrives Each hour the loop covers more of what is left

Talk it over with an engineer, in confidence
0203 0868633

What the recorder does to that disk.

What that loop is doingRecording travels down the disk, hits the end, returns to the front, and lays new video onto old. Leave the power connected and that cycle just repeats. Nothing gets deleted, nothing accumulates anywhere you could go and retrieve it, and no undo exists.
No one can quote your windowNot down a telephone line, and not from a model number either. It turns on which disk was fitted, the count of cameras writing to it, what resolution and frame rate they use, the codec, and whether the unit records all the time or on movement alone. Any figure given without seeing the system is guesswork.
Where the answer really isOn the unit. The playback calendar lists an oldest date against every camera: note each of them. That is your position today, and it advances for every hour the recorder stays powered. Do this first, before anything else is touched.
What overwriting actually meansOne value at a time is what a block on a disk can hold. The moment new video occupies that block, what sat there has ended, and no earlier layer waits underneath to be recovered. Where the loop has crossed part of your period only, video often survives that the index no longer lists, and that we go after. Where it crossed the whole of it, nothing comes back at all, whatever a firm may tell you.

What the symptom usually means.

Not listed? Tell us what it does →
What is going onThe usual reason for itWhere that leaves you
The recorder is still runningEach hour of running spends the oldest hour on the diskTake it off supply now
Nobody told you how far back it holdsCapacity, channel count and settings all shift itRead the earliest date
One camera reaches further back than anotherA quiet view recording only on movement uses almost nothingEvery channel is read separately
The unit stopped a fortnight agoIt stopped overwriting when it stopped writingLeave it off, post us the disk
Your date is gone from the calendarVideo can outlive the index that listed itThe free check answers yes or no
No claim opened yet, and no enquiryA disk moves far faster than paperwork doesCopy it today, not later
How it reaches us:send it by tracked, insured post; Guildford takes it in, and the leg home is on us. Unsure what should travel with it? A call before the box is sealed will get you an engineer who can say what to include and what stays behind. The whole of it is spelled out on theguide to packing and posting.

The sequence we follow.

Other jobs on the log →
01

Logged the day it lands, and the first look costs nothing Free

A case number goes on it the day the parcel lands, and an engineer settles what has truly failed before anything else happens — free of charge, and first in the order of work. Back to you come two things together: a straight note of what is liftable and what is not, plus one figure, fixed and written down. Accept it, or decline and owe us nothing.

Nothing to pay for lookingA single figure, put in writingNothing owed at this stage
02

No further writing at all

Nothing is played back on the recorder; it is stood down first. The disk then comes out, and a sector-by-sector clone is made through hardware incapable of writing. Once that clone exists, your position can get no worse — whatever the loop had not reached is now in the image, past the reach of anything that happens next.

Off the mains first of allCloned on hardware that cannot write
03

What the dates actually say

What the image genuinely carries is settled next: the earliest recording on it, the latest, and each gap lying between them. Where the loop has crossed into your period, every half-hour gets marked present or absent on a list, and that list reaches you in writing before anything further is tried. It costs nothing. The work after it is £400 + VAT, and on most jobs nothing returning means nothing to pay.

First and last dates written outEach gap listed
04

Exported, hashed, handed over

Anything legible leaves on fresh media as an exhibit — the files the recorder wrote, a copy any machine will play, plus MD5 and SHA-256 computed against each, and a dated custody record. That is the package adjusters and investigating officers look for. One further benefit: the footage now lives somewhere beyond the recorder's reach, so the box can be put back to work and the loop stops mattering.

Hashes, an index and a dateHeld where the recorder cannot go
05

You see the file list before you pay

What was recovered is listed for you first, and only then does a bill exist. Approve the list and it is invoiced; turn it down and it is not — and where nothing has come back, most jobs carry no charge whatever. Recovered data travels home on fresh media bought in for your job, with the postage at our end. Your case is not closed until you have read those files on a machine of your own.

No charge until you accept the figureFresh media, supplied with the jobThe post home is ours

What the bench has learned

  • Hardware moves faster than paperwork — weeks is what a claim or an enquiry takes. Copy the footage now and settle the invoice later.
  • A unit that has stopped is often the lucky one — a box that quit a fortnight back quit overwriting at the same moment, so what was on it then is on it now.
  • The cameras are not equal on disk — a view over the street door and a view of a back stockroom eat space at completely different rates, and where recording runs on movement the quiet one will be sitting on far older material.
  • Look for a second disk — larger recorders take two or more. One might be an archive; one might hold a retired group of channels that goes back further than anything live.

One thing halts it, and one only: cutting off the supply. Not a setting, not a menu option, not a message left with the installer — it is the switch on the wall. It has to be your own system, or one you may lawfully have examined. From then on you set the pace. If a place truly cannot go dark, put the hours you want onto a USB stick using whatever format the recorder writes natively, not a conversion of it, and talk to us before anybody handles the drive. The one approach that fails is to leave it powered and hope. Every hour of running costs an hour you used to have.

One job, followed all the way through.

LDN · ADR-2026-3425JOB LOGGED ✓

An Ealing unit, off the mains by nine

An intrusion overnight. The manager found the side door standing open, reached for the socket before touching anything else, and cut the recorder's supply. He rang after that. It reached the bench on Tuesday, and an image was made before anybody played a clip. The full night was there, camera and timestamp against every clip, and the adjuster held a copy within the week. What surprised everyone was how little the disk had been carrying.

The footagecame back entireHash-verifiedcopy handed over

What helps, and what harms.

Do this much first

  • 1. Photograph the live screen, clock included
  • 2. Unplug the recorder at the socket
  • 3. Ring before anyone opens the unit
  • 4. Tell the insurer, in writing, that it is preserved

What sets us back

  • Leaving it plugged in
  • Holding off until somebody asks
  • Telling the installer and then waiting
  • Putting the disk into an office PC

The questions that come up first.

How far back will my recorder go?

From here, nobody can. Nor will the model number decide it. Five variables set the window between them — disk capacity, how many cameras feed it, the resolution they run at, the frame rate, and whether recording is constant or triggered by movement. The recorder knows. Its playback calendar carries an oldest date against each camera, and that is today's honest figure. It will be a day worse tomorrow.

Once the loop has written over a clip, is any of it left?

No. When new video goes into a block, whatever was in that block has ended, and no software and no bench brings it back. A clip the index no longer points at is a different case: the video is still down there, unlisted, and can often be pulled out by pattern. Telling one from the other is the job of the free check.

Should I cut its power?

Yes, provided the place can manage a day or two uncovered. Nothing else halts the loop with any reliability, and pulling the mains lead is free. If the cameras have to keep running, get your hours out to a USB stick before anything else, written in whatever format the recorder uses natively and not a conversion of it, then ring us before the box gets opened.

My insurer has not asked. Does it matter?

Secure it anyway. A claim or an enquiry moves in weeks; the recorder moves at whatever pace its settings set, and that is nearly always the quicker of the two. Requests arrive later in writing, naming dates that have been round the loop again since. A copy made today is cheap and closes the question either way.

Begin here if yours is doing the same thing.

Copies the police and insurers take → A card that reads empty → Pen drives and USB sticks → Work that reaches court →

Off the mains first, because that is what protects the evidence.

Whatever holds the evidence, take it off power before anything else — a recorder that is still running overwrites its own oldest material, hour by hour. Send it to us after that. Looking costs nothing; recorder work is £400 + VAT and forensic instructions start at £800 + VAT, both settled in writing beforehand. What sits on that disk stays here.

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Price my job Sending it to Guildford