Before November 2 1936 when the alternate weekly 405/240 line transmissions began, the Baird 30 line system ran with regularity on the BBC Brookmans Park twin medium wave transmitters 356m and 261m (National and Home) in 1929. One transmitter was for vision and the other for sound. Of course such low resolution images as produced by the Baird system only needed minimal bandwidth.
After regular radio broadcasting ceased at about midnight, the transmitters would be handed over to Baird Television. The programs were listed in the BBC Radio Listings Journal "Radio Times" in the early '30's.
A few years ago, Doug McLean restored some of the Baird BBC broadcasts and here is on YouTube a recording of performer Betty Bolton in about 1933/34extracted and restored from a standard 78 RPM disc. I believe the actual images would have looked somewhat better as the BBC transmitter was equalized to over 10kHz for video in 1933 and 78 RPM home recording at that time would be lucky to reach much over 3kHz.
https://www.youtube.com/watch?v=G3CFkK5OORw
Baird Television Ltd. made Britain's first television broadcast, on 30 September 1929 (picture only) from its studio in Long Acre, London. Simultaneous transmission of sound and picture was achieved on 30 March 1930, by using the twin BBC new twin transmitter. By late 1930, 30 minutes of morning programs were broadcast Monday to Friday, and 30 minutes at midnight on Tuesdays and Fridays, after BBC radio went off the air. Baird broadcasts via the BBC continued until June 1932.
The BBC began its own regular television programming from the basement of Broadcasting House, London, on 22 August 1932. The studio moved to larger quarters in 16 Portland Place, London, in February 1934, and continued broadcasting the 30-line images, carried by telephone line to the medium wave transmitter at Brookmans Park, until 11 September 1935, by which time advances in the EMI 405 line interlaced all-electronic television system made the electromechanical broadcasts obsolete.