Its easy enough to bypass the immobiliser, send me a PM if you want to know how. Takes 5 mins, if Lotus put them all in the same place! Or can lend you a jump harness if that helps to rule it out.
Thommo - if it’s not the crank sensor, the immobiliser has an internal relay that controls the feed to the coil - might be sticking?
Try bypassing (as JDS, above) to see if it cures. Then you can always fit another immobiliser 
MattyB - again, try bypass. If that solves then it’s the immobiliser and that can be replaced.
Thanks for offers and info. Fingers crossed as Pesky says for a first time start this aft.
Who would believe it - cars with personalities and memories for how they have been treated 
May be I should be a wife beater, 'cos cosseting doesn’t seem to work.
Further twist - Paul Mattys have fixed the car, but it wasn’t the immobiliser, it was caused by two faulty fuses? Will know more when I collect tomorrow, but I checked all the fuses myself, and the repair bloke used his special tool on them to test also.
Are there more fuses than the ones in the front bay and behind the seats?
Nope, thats the lot. If it has blown the ECU fuse behind the seat, check the IAC valve bracket. Have seen them break, this then allows the valve to rub against the block. Eventually this wears through the insulation on the wiring and blows the fuse. Normally round a right hand corner.
let me know re my problems
So turned out that two of the fuses, behind the seats, were ‘faulty’. Although they tested ok with that illumination tool, seems they weren’t doing their job. Replaced - and with a pop and crackle, I was away!
Fecking expensive fuse swap though 
Took them a few hours to locate the problem, it seems…
Lol just had this today - turned engine over till the battery expired - charged it up for 2 hours - started first time
Think I,m the only one with a VHPD that behaves itself but then I do talk to it-SAAAAAAAD!
Noooo … you have now cursed yourself !!
lol…