Where you parked is a No Stopping contravention, except if loading is being carried out, (20 minutes max). You don't say whether you were loading or not, so were you ?
If you weren't loading then the contravention seems to be made out, but this doesn't mean it's game over, because there are a number of flaws in TfL management of the enforcement process that have won appeals in the recent past, so wait until the experts on this have commented. However, don't miss the pay or appeal deadline on the PCN.