There was a puritanical streak amongst the top echelons of Mullard management you know. As well as competitor product analysis, Mullard kept a weather eye on the advertising and technical literature of their contemporary competitors. I have here a company memorandum dated 1953 which detailed their concerns with the following photograph which was said to demonstrate sexual overtones not ideally suited to the wholesome promotion of thermionic products: -
The report does not go on to say whether or not it is the model's Mona Lisa - esqe smile or the implied message that size matters that may have caused a maiden aunt to flush or a stout young blade to swap his well thumbed Gamages foundation wear and corsetry catalogue for the rather more prosaic Cossor valve manual.
But Mullard's would never use such subtle suggestiveness in their literature as you will see in the following example photograph taken from a piece of early 1950s advertising material, note the demure smile and the buttoned collar that served to inform without inflaming the unwary reader: -