Jim Carroll - I need to correct myself after our conversation last night - air brakes were used on SOME British railway companies a long time ago, but did not come into general use until some time much later (the 90's, I think), & most standard gauge heritage railways.! Sorry if I misled you!

https://en.wikipedia.org/wiki/Vacuum_brake

http://www.railwaysarchive.co.uk/docsummary.php?docID=290