Morning Mark - True, The Light prog before Sept 67, was on both LW & 247m MW (1214khtz) When Radio Scum started, it took over 247 & left the LW to Radio screw. 247, was always a mess of multiple TXs, rather than one really high powered TX at a central or a good coastal location (for the more efficient earth)
This BBC PDF has it all, right back to 2LO

https://www.bbceng.info/Technical%20Reviews/dev_am_tx_nw_6a.pdf