In my previous post I neglected to mention that the direct tracking was offered to us throughout the week without a request from us.
After a discussion with ATC prior to this topic hitting PPrune we agreed with them that a direct track wasn't always a good idea.
Our direct tracks during the week were obviously into areas of little potential conflict.
Plodmans post sums it up.
If your route contains a sizeable dogleg then you are candidate for conflict if you take a direct track. You just need those pieces of swiss cheese to line up!!