There is another thread on whether compartment coaches could work again at
www.railforums.co.uk/threads/could-compartment-coaches-work-again.165069 and a separate thread on the 1988 Deborah Linsley murder at
www.railforums.co.uk/threads/30-years-ago-the-murder-that-ended-the-compartment-carriages-on-sr.162277
According to the Wikipedia entry on this incident, it is thought that she may have chosen to travel in that carriage because it was one of the few in which smoking was permitted. I thought that at least by the 1980s the remaining non-corridor compartments were generally non-smoking, and instead smoking was usually allowed in the saloon trailer on 4-EPBs with compartments. Presumably this was because it was thought that smoke would have more space to circulate in saloons, and that even smokers themselves could choke on smoke in the confined space of a compartment. I think Network SouthEast abolished smoking accommodation altogether on suburban services in about 1989/90, so only about a year or two after this incident, though.