As an engineering student new to London in 1954, I became addicted to RFH concerts, after my 100th visit on 19 January 1958, I wrote to the management (T E Bean!) and was invited on a backstage tour (with several young architects). On 30 January 1958, being an engineer, I was especially impressed on being shown a jet engine in the basement, reportedly used to operate the air conditioning system. If this was true, it must have been removed years ago!