My copy of Russell Meiggs’ The Athenian Empire (reprinted 1975) contains two (numbered) tickets to a lecture on ‘The story of three Roman sites saved for the nation’. This was a lecture hosted by the Welwyn Archaeological Society in the mid to late 1970s (and with a tpq, I suspect, of 1975). I would imagine one of the sites was the Roman bath-house under the A1(M) at Welwyn.
Can anybody provide a little more information?