THIS column has been called many things, but nothing could quite excel Peak resident Barry Greensted's description. It came about after we made reference to Colonel Howard Bentley-Marchant who serves with the British Forces here. Wrote back Greensted: ''Bentley-Marchant. Well, well, well. There's a name from the past. Haven't heard from Howard for years. ''I must say your column is better than an old school magazine, what?'' Of his old schoolmate he disclosed: ''Howard was a prefect - and a damned strict one - and a hell of an athlete.'' He also added that ''Howie was a fine guitarist'' and had the girls ''swarming at parties''. Greensted goes on, but we've probably given the Officers' Mess enough ammunition on Bentley-Marchant to be getting on with.