Does your fuel pump start off high in pitch and then get lower as the pressure builds up in the system?

IMO it is down to one of two things, but most likely one.

1) Fuel accumulator is tired and is leaking fuel back to the tank (most likely IMO)
2) fuel leak somewhere - it may only be misting, but again it would not help.

I take it if you flick the car from cold between key positions 1 and 2 about 5 times to prime the fuel pump the car then starts fine?