Ok, so is there anything to note looking back through the last few week's records? The recent round of problems started on 6th March and was acute enough to force me to walk. Within 2 weeks I'd done a 30km week in new shoes! In retrospect this was madness although there was a sort-of-logic in trying to use cushioning and supportive shoes.
Moreover, I have noted that I did a bit of heel striking in the new shoes to try to utilise their cushioning. Not only was this a change in gait but it's a gait that is suspected to lead to joint pain! For some reason it gave me ITB localised pain very quickly which forced me to sideline those shoes. Their heel to toe drop of 8mm is equal to that of my main road shoes and nominally 1mm less than my trail shoes (I say nominally as they squash down rapidly) so that simple parameter shouldn't have been an issue. For a few days I walked in and out of walk in zero drop plimsolls which felt good at first, but then set me back, perhaps...
A 2km increase per run was too much and although I've not specifically noted it I'm sure there was some background 'niggle' that I was running through. Certainly early in April I was 'aware' of my knees after 20km runs and that should have been a sign to cut back. Instead I ran twice like this with 4 four days and then pain recurred. I really think the overuse was more of an issue that the flat shoes.
It's now nearly 3 weeks since my last serious run - I've jogged 5km to and from circuits on one occasion - and once again things seem to be settling down. I've walked in Cornwall and around Sheffield and noted some discomfort but that feels to be less frequent and less marked when I notice it. The key thing is that it's still there showing underlying problems. There is an argument that tissue damage is present before you feel it and thus pain is a terrible indicator for when to stop!