There is a copy of this series on Demonoid, but I found this one on thebox.bz, which specializes in BBC TV. These are mpeg rips taken from old VHS tapes, so the quality is ok, but no .srt files. Thanks to the OL, and the info below is from Wikipedia.
Chelmsford 123 was a situation comedy produced for British Channel 4 television by Hat Trick Productions. It ran for two series, of six and seven episodes, in 1988 and 1990.
The series was located in the British town of Chelmsford in AD 123, and concerned the power struggle between Roman governor Aulus Paulinus (Jimmy Mulville) and the British chieftain, Badvoc (Rory McGrath). Britain is a miserable place, cold and wet – just the place to exile Aulus for accidentally insulting the Emperor's horse, but also give him something useful to do. Aulus was a rather delicate Roman, who was usually outwitted by the scheming Badvoc, who hadn't had a haircut for twenty-five years. Many of the other regular "Hat Trick" actors, previously seen in shows such as Who Dares Wins, also appeared.
The first series is now available to rent from 4 on Demand.
• Rory McGrath -- Badvoc, British chieftain
• Jimmy Mulville -- Aulus Paulinus, Roman Governor of Britain
• Philip Pope -- Grasientus, Aulus' Brother in-law. (and theme tune writer)
• Howard Lew Lewis -- Blag
• Neil Pearson -- Mungo
• Erika Hoffman -- Gargamadua, Badvocs girlfriend
• Geoffrey McGivern -- Wolfbane
Also appearing in a number of episodes were :-
• Geoffrey Whitehead -- Viatorus, engineer, bringer of rain, sculpter (unable to do noses, "not all elephants have trunks"), ...
• Andy Hamilton -- Taranis, British "warrior" and sometime programme associate.
• Chris Langham -- The Gate Guard.
• Bill Wallis -- Emperor.
• Arrivaderci Roma -- 9 March 1988 (sections in Rome played entirely in Latin, until Aulus arrives in Britain)
• What's Your Poison? -- 16 March 1988
• The Girl of My Dreams -- 23 March 1988
• One For The Road -- 30 March 1988
• Vidi Vici Veni -- 6 April 1988
• Peeled Grapes and Pedicures -- 13 April 1988
• Heads You Lose -- 9 January 1990
• Get Well Soon -- 16 January 1990
• Bird Trouble -- 23 January 1990
• Odi, et Amo -- 30 January 1990
• The Secret War -- 6 February 1990
• Mine's a Double -- 13 February 1990
• Something Beginning With 'E' -- 20 February 1990 (as with first episode, sections in Rome played entirely in Latin, until the Emperor arrives in Britain)