Barbara Dunn, G6YL was the first British transmitting radio-lady - her amazing story and some beautiful old photos can be found here: "Tribute to Barbara Dunn".
When I came upon that page at the very first time, I've noticed the unusual transmitter with a spectacular Marconi vacuum tube (I prefer to use term "valve" in this case), described in the text as "Her original transmitter employed an L.S.5 in a Hartley circuit". Digging the Net I discovered (here⬈), that that Hartley has been turned into the TPTG transmitter later. Unfortunately I had not found any more information about this radio - neither drawings, nor interior view. As it turned out then, my friend Lou, VE3AWA has looked for this information too, so we joined our efforts.
In a word, here it is:
I really appreciate Peter, G4XEX, volunteer operator at the RSGB National Radio Centre, who took these detailed photos and allowed me to publish them on the Internet. In email communications of August 2013, Peter told that he would help "in case anyone else wants pictures of anything we have at the NRC".