All budget TRVs and lockshields seem to be 15mm.

Would a Push Fit Single Socket Spigot Elbow 90 15x10mm (HD4A/15W) allow me to connect a 15mm TRV to my 10mm feed/return pipes? (dropping down from the ceiling and emerging from behind the radiator)
Also, I'm guessing the TRV would come with a brass olive that I'd need to replace with copper?