My sister, who had not flown on BA in over 10 years and 4 kids, who had never flown on BA before, were all upgraded from WT-WT+ a couple of days before the easter holidays began (they were on G-RAES too, so got the new cabin), so perhaps BA is targeting potential new travellers

....or they simply bumped up 5 people from seats in WT+ and it was easier to select a group of 5, rather than have to pick out 5 individuals