Ok, so the pulley is very reluctant to come off. Desperate times call for desperate measures. Out came the angle grinder to remove about an inch off the back of the pulley.
The two legged puller had proved unsuccessful in getting the pulley to move. This was mainly due to the fact that it would shift and twist when a load was applied and therefore would not pull straight. I have decided that a three legged puller may centralise the load and apply a direct force in line with the crankshaft, which might get the damned thing to budge. The three legged puller however, did not have sufficient reach and so the pulley needed cutting.
I shall leave it under tension and keep applying the oil to see if it will eventually move. The last resort is to try and cut the pulley off, but I don’t really fancy this option.