Eric Partridge, Dictionary of Catch Phrases: American and British, from the Sixteenth Century to the Present Day, No, no,” they shouted. “You can’t wear it like that. You look like a pox doctor’s clerk (pronounced clark).” D. Ireland Glass Canoe (1982) 15: They [...] ran into another mob of guys that shouldn’t have been out on the street. Only kids and dressed like pox doctors’ clerks.

G. Kersh Thousand Deaths of Mr Small 345: Don’t come dressed up like a pox-doctor's clerk. Come dressed like a human being. They say as it was one o’ they old-fashioned bombs as they dropped first of all, mum, as didn’t all goo off, but laid in the ground till summat touched ’em”. J. Byrell (con. 1959) Up the Cross 8: ‘Wheredya come by your china? [...] He comes up like a pox doctor’s clerk’.R. McGregor-Hastie Compleat Migrant 106: Clerk, pox doctor’s, to be dressed up like a: to be over-dressed. G. Seal Lingo 198: Other uses of up include the sartorial dressed up like a pox doctor’s clerk dressed in a lurid, flashy style. The Pox Doctor's Clerk is the moving and entertaining memoirs of one man's experiences as a volunteer in the casualty department of a Leicester hospital.

It was explained to me how a derby must be worn. The fashion is set by the young blades of Mayfair. Culotta’s 1957 novel, They’re A Weird Mob, holds the earliest citation, says Laugesen: “Jimmy whistled two notes softly, and Joe said, ‘Gees Nino, yer done up like a pox doctor’s clerk. Yer don’t need no coat an’ a coller an’ tie.’”Ah, but that wasn’t all, mum. When our Syd looked down into the hole that contraption ’ud made he see a shim of summat, an’ he waited till the smoke ’d all gone an’ then he got down to see what t’was”. The second-earliest occurrence of the phrase that I have found is from They’re a Weird Mob ( Sydney: Ure Smith, 1957), a novel by the Australian author John O’Grady (1907-1981), published under the pen name of Nino Culotta: I had a shower and changed my clothes. When I came out of the room, Joe and Jimmy were sitting in the lounge drinking beer. Jimmy whistled two notes, softly, and Joe said, ‘Gees, Nino, yer done up like a pox doctor’s clerk. Yer don’ need no coat an’ a coller an’ tie. Too hot, mate. Take ’em orf.’ Viewers of real-life medical programmes and medical dramas will be all too familiar with the grisly details and the tragedy in the 'cas' which is, perhaps by necessity, tempered by humour and moments of light-heartedness. At the fifth hat shop, I found one. Currently there is a run on derbies because they suddenly have returned to popularity.