I have a Trophy 900 in the same colour. Two blues are listed for 91-92 Caspian Blue and Caribbean Blue and I cannot remember which it is although I think it is Caribbean.
What I can tell you is the Vauxhall Nautilus (available from Halfords in spray cans) is an almost exact match to the point that I used it to cover scratches on both the tank and the fairing on my bike and after polishing with T-Cut and applying clear lacquer, I cannot spot the difference.
Link to Triumph paint specs is
http://www.triumph.co.uk/uk/2046.aspx