Interestingly it is chalked Sold which would date it as after mid August -it was scrapped by R S Hayes Bridgend. On the same day 5418 was also photographed similarily marked which met the same fate. 6712 was in the background of that shot which was last observed at Swindon on September 11th so it is after that date and I suspect all of them were being prepaired for transit to South Wales - note that the vacuum pipe is connected to the loco behind.