Thanks for the replies.
Simon; it doesn't look like tearing to me, and in fact the reason I dropped the pressure was because I had obvious tearing previously (although the tear pattern was ambiguous; I wasn't sure if it was hot or cold tearing!). This looks to me like melting. I have used the same rear setting everywhere, as I'm not usually that hard on tyres. Maybe I'm getting faster as I get older?
Scotty; I wondered if the tyre could be cold on the left, but I thought that looked like overheating! As for gears, well obviously I am a track god. Or maybe just slow. I hit 3rd as I exit the Bus Stop, 4th as I hook it left, and then 5th as the bike drifts right before I straighten, then 6th after I hit the grid markings (I think). A dab of the brake passing the pit exit and 5th all the way to Edwina's, 3rd for that, up to 5th before the hairpin, and 2nd until after the Bus Stop. Unless I miss a gear, which is not unknown. My SV is one of the slowest bikes on track, so I generally get passed on the straights, but often get them back on the brakes, or round Gerrards. Bearing in mind I am now back in the novice group, as my reactions and strength drop.