Moss

Starting a cold car can take a lot out of the battery.

How often was the car used before the problem? A few long drives per week or perhaps during this pandemic a few very short trips to the supermarket and then nothing for a relatively long time between.

A trickle charge may only maintain a battery that was fully charged in the first place.

If the car has only been used intermittently and not driven long enough to replace the charge taken by each starting cycle then the battery could be well down on capacity and you latest starting has taken it down to something like fully discharged. With only a "trickle charge" in these circumstances it may take a week or more to put enough charge in the battery to enable it to start again.

What is supplying the trickle charge?

That should be " Immobilisers SHOULDN'T stop the central locking "

If it is the case that the battery is towards its fully discharged state it may take 1 to 2 hours with the engine idling to fully charge it again

- maybe 30+ minutes of reasonably fast continuous driving (longer if power is being taken by lights, heated screens etc.)

A modern alternator never chucks all its possible output into charging the battery.

Assuming no other load than engine electrics, it makes no difference how fast the vehicle is going - it will charge the battery at its maximum rate at just above idle.