60/40 seat: 60 jammed

My '98 Freelander has a 60/40 split rear seat. The 40 lifts and folds forwards but the 60 will only fold down as the release mechanism has locked and the seat will not lift.
Has anyone any tips on releasing it, please?
I'm fitting a towbar and need to lift the seat to remove the panel and access the rear lights to complete the wiring for the electrics.

I have now accessed the mechanism at the centre of the car and find that is unlocked. Presumably there's another catch towards the middle or outside edge of the seat? it is there thet the problem appears to be. Help, please.

Yes there are 2 catches on the larger seat base, these catches will not dis-engage until the back rest is fully forward so try pushing down on it and see if the catch releases, if not see if you can access the centre catch as this is connected by a bar to the other catch, perhaps the bar has become detached.

Thanks Mantamad. I went out first thing this morning and still couldn't shift it but then when I got my wife to sit on it...result. Now i just have to make sense of the wiring pictographs...