Time-stamp drift — clocks unsynchronised

ANPR system clocks must be synchronised (commonly via NTP). Where timestamp drift is shown — through camera-side log or by reference to legal time (UK time signal) — the period of parking may be wrong by minutes or more, which can convert a within-allowance stay into an apparent overstay or vice versa. Demand the NTP source, last-sync timestamps for the period covering the event, and any drift logs. ICO surveillance camera guidance notes accurate time-stamping is core to data accuracy.

Legal basis

UK GDPR Article 5(1)(d) requires personal data — here the ANPR-recorded times of the vehicle's presence — to be accurate and, where inaccurate, rectified. The BPA–IPC Private Parking Single Code of Practice Clause 7.1 requires ANPR equipment to be fit for purpose, maintained and synchronised so that it records accurately, and Clause 7.3(b),(d) require images to bear an accurate time and date stamp subject to a manual quality-control check of the timestamp. Where the recorded entry/exit times are shown to be unreliable, the calculated period of parking cannot be relied on. This is an evidential challenge, not a guarantee.

How to identify this in your case

Marginal overstay; you can produce alternative timestamped evidence (text, dashcam, transaction) that contradicts the operator's times.

Sample appeal wording

Before you send this

Deadline. A late submission can be turned down without your argument being read. Check your notice for the deadline and how it is counted.
Paying may end it. Paying can count as accepting the notice and can close a challenge already under way. Part-paying or acknowledging an old debt can also revive a time limit that had expired.
The amount can change. Check what happens to the sum if you challenge — it may be held, re-offered lower, or keep rising, and fees or enforcement can continue meanwhile.
Use the official route. Use the method, recipient and form your notice specifies, with any reference, evidence and signature it asks for. Sent elsewhere, it may not count.
Only say what is true. Do not copy any statement of fact unless it is true for you, and check the legal point still applies. Delete what does not fit. It may be treated as your statement.
Careful what you volunteer. Avoid unnecessary admissions — naming the driver or accepting responsibility can remove arguments. But answer anything you are legally required to answer, and do include the evidence your ground needs.
Keep the record. Keep what you sent, the attachments, any receipt, and the reply. Note the next deadline.

Sample wording to adapt and send yourself — it may not fit your notice or the stage you are at. Replace the bracketed prompts with your own details; leave any case citation as it is.

Dear [OPERATOR], Re: PCN [REF] — Disputed timestamps I dispute the accuracy of the timestamps shown on your ANPR images. Independent evidence of timing: - [Dashcam footage at TIME] - [Bank/card transaction at TIME at adjacent location] - [Phone call records] These show my entry/exit times differ from yours by approximately [X] minutes. Under UK GDPR Article 15 I require: (a) NTP source and the most recent successful sync timestamp before [DATE]; (b) Time-drift log for the period [DATE] +/- 7 days; (c) Camera maintenance records. Without reliable timestamps the alleged period of parking is not proven on the balance of probabilities and the charge fails (PoFA 2012 Sch 4 para 9(2)(b)). Yours faithfully, [NAME]

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Sources

UK GDPR Article 5(1)(d) (accuracy principle)
BPA–IPC Private Parking Single Code of Practice, Clause 7.1 and Clause 7.3(b),(d) (accuracy, synchronisation and manual QC of ANPR timestamps)