We’ve been offered a couple of rather nice sofas albeit one of them has a bit of cracking on a seat cushion.

Can anyone recommend anything to bring it back to life? Furniture Clinic’s balm and other places make out they’re up to the job but are they real or BS?

Ta

Don’t think you can repair the cracks but any oily moisturiser will restore suppleness. I would use Waxoyle, which as far as I can see is the same as Nikwax but much cheaper. Once the solvent dries off the leather should lighten up a bit.

http://www.furnitureclinic.co.uk/Leather_Furniture_Repair_Restoration.php

depends on the size and probably not suitable but you can get swish sticky leather patches on amazon to hide holes and maybe small cracks, although I guess yours are probably larger.

GLIPTONE

Its been used on vintage leather car interiors for donkeys years, no reason why it wouldnt work on a leather sofa, made just down the road from the Singletrack office too.
*edit – just noted they have a section for leather furniture too.