No Spark v 8 series 2 lpg

Started my series 2 v8 today -no prob- it was already warmed up, Idled for about 1 minute and then it cut out just as if i'd switched it off and it wouldn't start. Called the RAC, he checked the usual,fuses etc, discovered no spark, plugged his laptop in but it wouldn't read anything 'cos he didn't have a compatable programme. The rac guy said there were several possibilities including at worst coil pack breakdown and ECU.
Knowing my luck it's likely to be the most expensive part needed.
I'm pretty ignorant regarding modern electronics (I was looking for the dizzy ! )so can anyone tell me is there more than one ecu on my disco and how much is the one likely to be the cause of my problem going to cost me.
It's going into a local non- Landrover garage this week and I want to prepare myself for the worst case scenario cost wise, also has anyone suffered this kind of breakdown and got off lightly, all diagnostic suggestion welcome
Phil.

might be imobisler or summat,woodnee bother ya self too much.

check your engine earth straps too

Did the RAC guy check for fuel too? If there's no fuel it's most likely to be the crankshaft sensor. It's unusual for a coil pack to just stop dead without beginning to breakdown and causing misfiring first.