The problem was that the key internals were totally knackered and beyond any sort of repair, so they couldn't put the old internals into a new fob/key.
The only option was a complete new key & fob, and as I said I was told that an OEM one can be supplied pre-programmed and it will work right out of the box, but they're not cheap, £400 is the cheapest quote I got for a genuine Landrover one.
It’s worth asking the person mentioned, as the key may still be able to be cloned.
J