The cold weather had highlighted that my battery was at the end of its life so a visit to EurocarParts (currently offering 35% discount ) beckoned to change the battery.
On connecting the new battery, the alarm beeped every second together with some lights flashing (side, rear, instrument, under bonnet and cigar lighter). Pressing the fob only made a deeper tone beep and then the beeps continued. Only turning on the ignition would stop it - the engine would start and the car drive normally. Also, pressing the fob would not operate the central locking to lock the car, it would just keeping beeping. There was no obvious solution. Even disconnecting the alarm (siren) didn't stop the lights flashing. What was I to do
Finally, I found out (but not from any Jaguar literature) that you are suppose to programme your fobs to the alarm after each beep. I have two fobs but one doesn't work so for each beep I kept pressing the same fob. I think there were 5 beeps and after pressing the fob after each beep the beeping and flashing stopped.