S1 Wheels will not turn

Hi, I'm new to this site so apologies if I'm at the wrong place.

I've an 88' Series 1 Land Rover which has been lying in the same spot for 13 years and obviously not in a great state. I'd like to move it to another garage to start a slow restoration. I re-inflated the tyres, the handbrake lever is released and the gear lever seems to be in neutral but when physically pushed, the vehicle will not roll forward or back, as if the brakes were applied.
When I jacked it up to remove the wheels for tyre re-inflation at a garage I noticed that the back wheels would not turn when both off the ground. I didn't try this on the front ones though.
Can you suggest possible causes and solutions?
Many thanks.

Is it in gear and clutch bound ?

If not bound brakes

i'll guess there's lots of rust in the brake drums after 13 years

I guess it would be the brakes, try removing the rear wheels and see if you can release the adjuster, if not work your way round the drum with a decent hammer (not too hard!) to see if the brakes will release.

If you think it is the drive train that is locked up then remove the propshaft although I dont know how feasible that is when you cant turn it to undo the nuts?

Back wheels won't turn when both off the ground sounds like brakes unless the difflock is engaged - did a series one have a rear axle difflock? - I've never worked on one.

+1 on the brakes but how hard did you try to rotate the wheels - have you tried dragging it with another vehicle sometimes that is the only persuasion they need - they'll need sorting anyhow so don't worry about 'breaking' them.

Jack up, wheels off and a few sharp taps around the outside of the drum with a lump hammer - NOT the narrow edge but the face of the drum near the edge - take care not to wellie the studs - you aren't trying to knock it to Australia - just enough to shake it loose. If you feel more wellie is needed get a bit of 4x2 wood lay it on the drum and wollap it ... the drum mind you NOT the end of the half shaft.

Might help to get some heat on it too - I mean real heat a torch that can use MAPP or MAP-Pro gas get hot then wollap again - if that doesn't move it nothing is.

You didn't say if the front has the same problem - is this just the back?

Was it parked with the handbrake on ? - if so you may also need to fettle the transmission brake too - or remove the propshafts.

can also put a pipe between studs with wheel off and lever it a little

With the gearbox in neutral, see if there's any movement in the diff by rotating the propshaft. If there's even a bit of play (who am I kidding? there's gonna be lots) then it's probably the brakes. See above for solution.

Many thanks for the quick replies - will have a go next time I'm there.
Yes, there's plenty of rust around the wheels, so probably that's the cause.
Thanks again.