ETAS is E Tonks & Son. I have two, one of particular is a unusual lock with 4 sets of pins. Both the locks I have are v.well hand made pre-1960s.
They manufactured locks in the home of English lock making, Willenhall (Had to mention that at one point on the site) before being taken over by Union I think.
Like most english locks they are crap. The english have a fine tradition of gettting things close then ripping into it with a file to match. ERA locks for example sometimes use 2-3 spacers between levers just to get them to fit. AS for the ETAS they dont make them any more but use a silca ETA1 key blank - but many a fool has used a silca YA1E (yale) key to try and make it work. They made 4 pin locks and 5 pin as well (same key but shorter)- the pins were rounded not pointed like the LAB pins you would use in a lockwood LW4 (C4) keyway. they also used spool top pins which pisses you right off when trying to pick because you know the locks are crap.