Finally, the efforts paid off. There was an unanticipated extra cost as I found out that the injectors were seized solid and needed new nozzles. Not cheap, but the very efficient diesel experts ordered the bits straight away and I got my injectors back, nicely cleaned into the bargain, inside 2 days.
It didn't take long to bolt them in and get the lines bled. I finally and with great anticipation turned the key on Saturday afternoon, after the engine warmer had been plugged in for a couple of hours. To much joy it fired into life just after just couple of turns. Although the joy was relatively short lived as it proceded to blow a large quantity of very watery hydraulic oil (also the gearbox oil) out of one of the fittings at the back. You can see the joyous moment here as it's easier to post videos on Blogger.
After fiddling with a couple of the many levers, we were able to start again without any major hyraulic leaks. Without taking it significantly over a slow idle we drove a short circuit, managed to get all the gear levers working and figure out some of the hdyraulics.
Plenty more to do, starting with the gearbox oil (all 18 Litres of it!) and it'll need a new earth strap and battery lead before it can be expected to start reliably.
I'll do the gear oil sooner rather than later and then that's more or less it for the winter. This is were I had hoped to get to. It feels good to know that the engine's back in one bit, protected from the elements and has had oil pumped around it.