No luck with trying to source this PSU, I did try a large number of suppliers who were helpful but they came back with nowt. Stone had one but it was not a sale item but a spare for an under warranty customer and I couldn't pursuade them to let go of it. So close!
Was about to give up, but got chatting to an electrician and he told me to use a hair dryer and heat the capacitors up for about 5 mins on with it plugged in. I laughed and said I might as well give it a go. Got a hairdryer and near enough five minutes of heating the PSU up, the PSU lights up! Server is now up and running!
I have had to use the hair dryer trick a couple times more when I moved the server and had to detach it from the UPS, but I am phasing this server out with a replacement as I reckon the hair dryer trick will eventually stop working.