[BRISTOLLH]

Hi there, hope you can help.
I have a 1979 Bristol LH with a Leyland 401 engine.
It was in passenger carrying use and then a driver training bus until around 2005 and since then it's been used as a mobile home and is now being recomissioned.
While it was lived in the engine was run evey few days to charge the batteries though the bus wasn't moved.
According to the then owner it started first time every time, and each time I started it on several visits this was proved correct and it fired into life after 3 or 4 turns of the engine.
It drove 350 miles back to my place at up to 55mph with no issues whatsoever, the engine never missed a beat and it was duly parked up.
Since then it has proved extremely difficult to start - having to crank away for ages and the only way it will start is with the throttle pushed right to the floor and keeping the starter turning as the engine starts to fire (reluctantly) until I can risk releasing the starter button.
As it ran so well previously and started each time while static I can only assume something has changed after the journey home. It had enough oil and I filled the tank to the top with diesel as I didn't know if I could rely on the gauge.
Any ideas as to what might be wrong?
On a seperate note I see it has two alternators, though only one has a drive belt - the other has it's lead disconnected. What would be the thinkign behind this and can it run on just one ? - batteries appear to be charging fine and charge light goes out when engine is running.
I look forward to your responses