fast

Finishing sehri at the last minute following an incorrect clock

Q:

1) Zaid followed his faithful bedroom clock for many years and he used to complete eating his sehri at the last minute based on the time on this clock. He recently compared his clock with the BBC time and found it to be 3 minutes slow. Is he muqallaf of following this time and repeating his fasts considering the possibilty that the BBC or any other central bureau time may also be incorrect.