BackPacker, before I posted my concerns about the apparently short length I checked with a FI who told me that, amongst other things, a reasonable dog-leg can be included. It is the word "reasonable" which is important, so a QXC of say EGBJ-EGBP-EGBS-EGBJ (landing at EGBP and EGBS) couldn't include a huge dog leg via Cardiff just to make up the distance.