Question Author
Thanks to everyone.
I guess I just believed the original ad when I took out the policy ("£10,000 bonus on maturity"!). I guess I don't really understand investment/finance (I had endowment mortgage, PPI, etc) and just trust the so-called experts. Bonuses have been around £50-£60pa. I can't find the original documents at the moment but you're right Tilly2 and albaqwerty. Getting around 30% return over the 15 years similar to tamaris which is a pretty reasonable return.
Thanks again BB