Cheers guys. I'm sure the NSS is fine, as the reverse lights are fine and it always goes into gear and starts correctly etc (I've looked into XJ NSS symptoms before!).
Dave, funnily enough I have recently fiddled with the TV cable, as I thought it probably needed adjusting after 30,000+ miles since I last did it. I've tried a couple of positions now, but I thought it just affects shift position rather than being able to make it slip?
Could you maybe explain to me how to adjust it correctly?
I adjust the XJ's cable almost every time I open the bonnet and I've never had an issue.