warning gong has started since having new rear tyres

Pre facelift has a connector which looks like a standard ISO radio plug - it isn't!

The connections are non-standard but it should have a permanent live. If you can find pin 7 which according to my diagram should have a yellow wire on the car's wiring, then that is the permanent live.

I did try pin 7 but that seemed to go dead when pin 5 was live and vice versa, i eventually went to see a friend of mine at Halfords who gave me a fusebox connector, which is basically a double fuse holder that you slot into the box in place of a fuse that does what you want (ie permanent live in this case) and had a connection wire leading out from a 10 amp fuse, you slot the original fuse in next to it and connect the input to the wire, problem solved
Neither of us could understand why the original harness seemed to have no permanent live so the supply to the stereo is now nothing to do with the cars original wiring, thanks for your patience with me on this ... even i was starting to get annoyed with myself, roll on the next problem which i'll put into a new thread

Did you check for blown fuses? The OEM radio would have needed a constant supply so there must have been one at some time.

I've used piggy-back fuse holders a few times, they are a neat solution to adding a circuit. Your friend maybe already did this or said about it, you need to fit the piggy-back holder the right way round. Check which end of the fuse holder (in the fuseboard) is the feed ie permanent supply, the common end of the piggy-back holder goes to that end (the end away from the flying lead). It's not the end of the world if it's wrong but the original fuse will be carrying its load plus the extra from your new radio which could cause it to blow unexpectedly.