Finally got to it ... hopefully
Had the weekend where the 126 made an appointment at the garage where they were taken to task in locating the squealer.
They checked the dics to the bearings and finally had a look at the rear hand brake shoe (which had a lot of dust and dirt). They zeroed in on the brake shoe and removed it to clean it through and through. It seems that solved the squeling, for now ...
126 tailed by a 203, 129 leading the pack.