It can be a hard slog trying to get damaged tyres replaced because they are 'faulty', they are sent to an inspection centre of the manufacturer and a committee sits and inspects and adjudicates over them but in 9 out of 10 times they rule that the damage was caused by 'due wear' or 'outside penetration', you can appeal but you're usually on a hiding to nothing. The only times you might get a result in your favour is if the cording in the wall inside the tyre gives way and the tyre bulges or it suffers from tread separation.

Which would explain the nearside damage but not that on the offside. I reckon that taking the wheel off will give a witness mark 

15 minutes ago, tomshepp said:

Which would explain the nearside damage but not that on the offside. I reckon that taking the wheel off will give a witness mark 

Fair point! 

I have also thought about them both being rears...  If they're cambered enough, most of the load will go through the inner sidewall and without any steering angle, the load won't ever shift around, unlike with fronts.  I do suspect there was a defect in these tyres personally, possibly the badging mould cut a little too deep (seems to follow the flats on the letters), or the XL banding was fitted slightly too close to the outer wall.  Either way, we'll never know now...