When the Desiros where introduced, I raised concerns from passengers to S.W.T management, (whom I admit where from a non railway background), that the lack of head code display was not a good thing! The only reply I had was well this is the new age and the public will get use to it!
This kind of manager had no idea of railway practice, and that two numbers displayed, could impart so much information. i.e 74 = Stopping service to Waterloo from Portsmouth & Southsea calling all stations halts and lampposts to Surbiton via Guildford & Woking, then Wimbledon and Clapham and finally Waterloo! Where as now all you will see is the word Waterloo!
If headcodes are to make a comeback, there will have to be an effort made by the new management of the Southwest franchise to remind or educate the public of the codes, but this could fit in with their look who's back theme!
Does any one else remember that the class 442's had a small display above the corridor connector, they didn't last long as they always seemed covered in dead Flies!