Hello & hopefully some help?

Welcome from Scotland. Just had a quick look on ebay ,pillion seat for £38 with bracket on sale now plus a few others any pre 2.5 pillion seats except touring models will fit . Go to motors ,motorcycle parts ,type rocket 3 an your in there. I take it your on IOM got friends there . Total Triumph has brand new backrest kit £380 on sale now ,second hand kits are harder to source .hope this helps .
 
So, I've got one guy still to come back to me but of the other 3 that have on e-bay, they've all said that the pillion seat is from 2005-2012; I've e-mailed Triumph to see if there is any sort of weird date/model thing about the 2004 model that suddenly changes for the 2005 onward version.

Thanks for all your help so far guys and please do keep the suggestions coming.
 
Ah backrests. I remember many, many years ago when my wife rode with me on my Yamaha 1100, I had a huge custom seat with backrest. I thought I would be cute and ride a wheelie 50 feet or so to impress the hell out of her (we had just got married). It did NOT impress her and I was told sternly, with smoke coming out of her ears, to take her to the house so she could get off . I was told I was on double restriction and her lady parts were on lockdown for a few weeks. Lesson learned.
 

So perplexing that the ladies just don't appreciate the same things we do. I'm lucky that mine does enjoy speed!