I'm guessing this was a mistake but the latest time I submitted to the leaderboards I put in with an IGT of 1:20:35 but it has now appeared on boards with an IGT of 1:16:17?

I calculated the IGT myself. Your time was 1:16:17

Interesting! Out of curiosity how did you calculate the IGT differently compared to LiveSplit?

I just used this http://www.calculator.net/time-calculator.html

The reason it's so different is because livesplit doesn't keep the true IGT; It still leaves in some of the load times.

Oh ok, fair enough. Been sat wondering for a while now how on earth we were gonna find some of the 5 minutes that the top times seemed to be ahead!