So my van sat for a month, and much to my delight started straight up.
The accelerator pedal felt like it had seized, until I kicked it and it started moving again freely.
As I started driving, I quickly realised I was stuck in first gear. After a run out the road it eventually kicked into second, but not third.
Checked under the driver's seat, and there was a lot of play in the throttle cable if I pressed and released the pedal. Played with it for a little while until it sprang back to a resting position more readily. Headed out the road again and presto! First to third no problem (I'm still having pesky OD problems ).

After this should there be anything else I should do to prevent this happening? Lube/clean anything etc?