Sten guy
Here is a link to an ad with the Thompsons you are asking about that is from 1977. Law Enforcement Ordnance Company (LEO) was very active in Thompsons. Roger Cox owned LEO or maybe was partners with someone not sure which but I know he was the main buyer and seller. Look at the consecutive pair listings, your items sought are the 1st ones.
Hope that helps.
michael
LEO ad from Blackriver Militaria web site