Can I challenge an ANPR charge just because the camera might have been wrong?

You can put the operator to proof that the ANPR data is accurate. Requesting calibration records and ANPR images does not require you to prove the camera was wrong — the burden is on the operator to prove the charge is based on reliable evidence. If they cannot produce calibration records or the images are unclear, the charge is not adequately evidenced.

What is acceptable evidence that an ANPR camera was calibrated?

Calibration records should show the date and nature of the most recent service, the engineer who performed it, and confirmation that the clock synchronisation was checked. A log showing regular periodic maintenance is strong evidence. A handwritten note with no technical detail, or no records at all, falls short of the Code requirement.

Does clock drift of a few minutes matter?

Yes, in borderline cases. If the alleged overstay was 11 minutes and the permitted period was 1 hour, a clock drifting 2 minutes means the actual stay may have been 9 minutes over — under some grace period provisions. In close cases, even small discrepancies can be determinative. This is why requesting calibration records in every ANPR case is worthwhile.

ANPR Calibration

By GetRighted Legal Research TeamLast updated July 2026

Summary

ANPR calibration is the process of maintaining and verifying the accuracy of automatic number plate recognition cameras used in private car park enforcement. Both the BPA and IPC Codes of Practice require operators to maintain ANPR systems to a documented standard and to be able to produce calibration and maintenance records when challenged. A camera with an uncalibrated clock generates inaccurate dwell time readings; a poorly maintained camera produces misread plates. Either error can produce a charge for a vehicle that did not breach the terms — or a charge based on an inflated dwell time. Inability to produce calibration records is itself a Code of Practice breach.

What calibration covers in ANPR systems

Calibration of an ANPR system covers two principal elements. First, time synchronisation: the camera's internal clock must be accurately set and must remain accurate over time. A camera whose clock has drifted by even a few minutes can record a dwell time that exceeds the permitted period when the actual stay did not. Second, image quality and recognition accuracy: the camera must capture clear images and the software must correctly read number plates. Dirty, obscured, non-standard, or damaged plates increase misread rates. Calibration records document both elements — when the system was last checked, by whom, and what adjustments were made.

The Code of Practice obligation

The BPA Code of Practice (Section 20) and IPC Code of Practice (Section 12) both require operators to maintain ANPR systems in good working order and to retain calibration and maintenance records. If a motorist requests calibration records in an appeal, the operator must produce them. An operator who cannot provide maintenance records — or whose records show the system was not serviced for an extended period — is in breach of the Code. POPLA and IAS adjudicators have upheld appeals where the operator failed to provide ANPR calibration evidence.

Always request calibration records in your appeal

In every appeal involving an ANPR-based charge, request the ANPR entry and exit photographs, the timestamp data, and the calibration and maintenance records as standard. This should be in your Stage 1 appeal letter. If the operator fails to provide the records, this is itself a Code breach — note it in your Stage 2 submission to POPLA or IAS. Even if the records are provided, examine them for gaps in servicing history or evidence of drift.

Using ANPR calibration in your appeal

✓In the Stage 1 appeal, formally request: ANPR entry and exit images, timestamp data for your vehicle, camera calibration records, and maintenance log.
✓Check the timestamp on the entry and exit images against your own records — receipts, phone records, fuel stops.
✓Compare the entry time on the ANPR record with any pay-and-display receipt or car park payment record you have.
✓If the calibration records show the camera was not serviced recently, note the gap and the uncertainty it creates about timestamp accuracy.
✓If the operator cannot produce calibration records, cite the specific BPA/IPC Code section requiring their maintenance and production.

Sources

BPA Code of Practice 2023, Section 20 — ANPR system requirements
IPC Code of Practice 2023, Section 12 — ANPR calibration
Protection of Freedoms Act 2012, Schedule 4, para 7(2)(b)

Frequently Asked Questions

Can I challenge an ANPR charge just because the camera might have been wrong?: You can put the operator to proof that the ANPR data is accurate. Requesting calibration records and ANPR images does not require you to prove the camera was wrong — the burden is on the operator to prove the charge is based on reliable evidence. If they cannot produce calibration records or the images are unclear, the charge is not adequately evidenced.
What is acceptable evidence that an ANPR camera was calibrated?: Calibration records should show the date and nature of the most recent service, the engineer who performed it, and confirmation that the clock synchronisation was checked. A log showing regular periodic maintenance is strong evidence. A handwritten note with no technical detail, or no records at all, falls short of the Code requirement.
Does clock drift of a few minutes matter?: Yes, in borderline cases. If the alleged overstay was 11 minutes and the permitted period was 1 hour, a clock drifting 2 minutes means the actual stay may have been 9 minutes over — under some grace period provisions. In close cases, even small discrepancies can be determinative. This is why requesting calibration records in every ANPR case is worthwhile.

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