Well that was painless - I think the KY Jelly helped.
Just to keep it all 'News' worthy - the police story does check out.
http://www.bbc.co.uk/news/uk-england-somerset-26864737
Apparently, because Melanie was raped and murdered there were good attacker samples but DNA technology is only now good enough to assemble them all and produce a complete profile.
I asked them how they knew I was me and they said they hoped I had my driving license - which I didn't. My business partner helpfully pulled a copy of one of our books from the shelf which has author photos on the back cover which they decided would be difficult to fake in the circumstances.
On a legal note, the form i signed said the sample would only be used in this investigation, not applied to the Police database, and then destroyed.
And they will let me know the result; negative by phone, positive (I assume) will be an early morning visit.
Seriously, Melanie's mother is still alive so for the sake of everyone concerned, I hope they get a result soon.