John
Great first post and welcome to the forum! Some really useful information here.
As you may have gathered from some of the earlier posts on this thread, quite a few of us are fascinated with the operation of 1960s/70s milk trains, including, of course, in South and West Wales. I mentioned John Vaughan's book The Power of the Hymeks earlier and there are some great photos around Cardiff and Newport including a cracking one at Marshfield showing D7080 shunting milk tanks (page 93). This clearly shows the hard standing you referred to.
You've now got me thinking South and West Wales again! Just a shame class 22s weren't regulars there.
Stephen