Thanks everyone for your replies. I have the plug in adaptors, but wanted something more permanent. I had hoped that someone produced a unit that replaced the whole ashtray area.
I have also looked at fitting the USB in the glove box, but I have mine full of CDs, yes I know, I could use the mp3s from my phone instead.... Also I want to assist the Jag satnav by using WAZE apps etc from my phone, and so wanted a USB closer to the dash.