I have just noticed that the camera date/time is controlled by my RLN36 NVR. This uses its own (undefined) NTP server.

I have set the RLN36 to GMT with no DST and it gets the date/tijme correct

I had to re-install a camera and did not set its time zone etc. but when I looked at my NVR the date and time were set correctly

It is possible that the localisation is done by my router when it sees a request for NTP?

Same here.

I have 14 cameras connected to my RLN36

All of the cameras and the RLN went to BST on Sunday 24 March.

My NAS devices are all OK

I have tried fiddling with the settings on one camera with no success.

The DST setting definitely says Last (Sunday)

I assume it is a firmware issue. I do NOT relish having to update al the camera!