So this is what they look like when they're new:
....got this new old stock beauty at auction on ebay for £73

It does have a bit of damage though, looks like it's been dropped, you can see the potentiometer on the top leaning over a bit

I've contacted the seller and hopefully I can get it replaced or some other suitable means of repair worked out.
It comes complete with imobiliser and armour. However my car doesn't have a keypad. As it's never been paired with a keypad what will happen? I'm hoping I can avoid having to remove the immobiliser.