Phoned allied, they want near 700 quid for one FFS. Took the old one off and it's the original so I suppose after 160,000mls it ain't too bad considering it's electric. Could have got one second hand for £150 but decided to go for new as I plan keeping the cab for a while yet, but not Allied's mega money one.
Onto trusty ebay and there a place does 'em brand new for £500.00. They wanted £535 but allow you to make an offer so got it for 500. Comes ready programmed so no need to go to dealer top get that done, Allied take £42 quid for that, just to plug into a laptop and press a few buttons

Job is pretty simple although I had to cut off the crimped clips that hold the hoses on ( that's how I reckon it's the original) It's coming up overnight so should be back on the road tomorrow.
http://www.ebay.co.uk/itm/BRAND-NEW-GEN ... 0847305843