Doing a bit of digging on OH and have just looked at his mobile history on his Orange account. It's showing that he used GPRS (internet) on his phone practically every hour throughout the night last night and has done on a number of occasions.
For instance last night he was on it 9.30pm, 11pm, 12am, 1.20am, 2.30am, 3.40am and 4.50 (at this point he would have got up for work).
Is it normal for orange to say he's been online all night like that? see what's weird is if he was at home, he'd be using the wifi anyway so why is he using mobile internet all night?