As pointed out in the earlier Delerium thread - the night Delerium are playing London is the same night as one of the Mission Farewell gigs (the 'Children' album one to boot).
This is really not good for Angus.
I'm now going to have to hunt down the rest of Delerium's dates and see what is viable.
Glad someone else saw through the haze of enthusiasm I was having and pointed this clash out to me before I brought any tickets! Thanks twisted_times!