Problem with auto box changing from 1st to 2nd

[The G Kid]

I'm loving driving my DB9 LM, but have one issue. Sometimes the auto box won't change from 1st to 2nd, and I can only get into 2nd by using the paddle. Once in 2nd and back in auto mode, changing from 2nd to 3rd, 3rd to 4th etc is fine. However if I come to a stop, and the auto box changes back to 1st, I have the same problem when I start off. If I stop, put in park and apply the handbrake, and then drive the problem usually goes away.

Also, the problem doesn't always happen, which makes it even more annoying.

It's been suggested the problem is with the foot brake switch, and the gearbox thinking I'm braking when I'm not. However if this was the case wouldn't it affect changes from 2nd to 3rd etc ?

Any help would be gratefully received.