Indurain's Lungs
Legend of Garry Nelson
It's the sport of mediocrity - if you're actually good in the water, or on the bike or running then that's your sport and you compete and win stuff. If you're quite good, but not competitive at any of the components then you do triathlon.
What race are you aiming for?
Well, I'm a mediocre cyclist and a mediocre runner these days!!!
Its the Southampton fast twitch at the end of April http://offbeat-events.com/event/southampton-fast-twitch-triathlon/
Given that you do have some swimming pedigree from your past and obviously have a pretty decent level of fitness, for 400m I would think you should definitely ok for a pace of at least 2:00min/100m with a small amount of training. If you can swim the full distance front crawl without stopping then it's hard to swim it a pace much slower than that!
Sounds good, if I add up those swimming, cycling and running times it should only take me an hour!!!! (No chance!)