Only just come across this - one of my favourite topics...
I don't know much about BR wagons, but 130 of the GWR W10 cattle vans were lightly converted for fruit and vegetable transport in 1939 becoming Y10.
The "ALE" were in fact for Guiness - originally W1 also converted in 1939 to V10. Most of the ones that were converted were the oddities left over from Lots 464 476 and 651 which had been built with 18ft length.
BTW although limewash was banned from use as early as the late 1920's I have personal experience of mixing and using it on the inside of cattle sheds in the late 1960's. I have always wondered how the ban really came about and how effective it was when the stuff was still in common use so many years later.