Can't really call TotP "rock"....
Having seen 100+ episodes of Top of the Pops, I would consider this opinion inaccurate.
List of Performers on Top of the Pops
Any recording act that had a single on the UK chart was eligible to perform on
Top of the Pops. Most, but not all, mimed on stage to the studio recording. Some performers sang live to an instrumental track of their chart hit, and sometimes bands performed their hit song live on the show.
I don't know if this is still the case, but the live musician's union in the UK was very powerful at one time. There were strictly enforced limits as to how much recorded music could be aired on UK radio and television. A song that was #1 on the chart might have been restricted to a maximum of three or fewer plays per week on BBC radio.
Top of the Tops was considered to be a 'live' performance per these regulations, even if the performers mimed to a studio recording. The show was taped on Thursday afternoon and aired early Thursday evening for most of its run. The UK is small enough that a band on tour could perform on that week's
ToTP show, and do a live gig somewhere in the country later that night.
One of the ways many acts circumvented the restrictions on broadcasts of their studio recordings was to perform their songs live in the radio station studio. This was done frequently on John Peel's BBC1 radio show; Peel was a very influential Disc Jockey, who sometimes hosted
Top of the Pops. Many of these 'live in the studio' broadcasts have been released commercially in recent years under the umbrella title '
John Peel Sessions', often as part of CD box sets. The ability to perform songs live in a radio station studio is one of the reasons why the British bands were often much better performers at live concerts than North American counterparts.
For charting songs for which the performing artist(s) were unable or unwilling to appear on
TotP, dance troups performed on stage to the recorded song, (often an edited 'K-Tel type version', about two - two and a half minutes long). Sometimes music videos were played in lieu of an onstage performance. The very early music videos were often 'zero budget' promotional films made by the record label. or sometimes
ToTP just played video of something to accompany the audio track. Later in the 1970's and beyond, professionally shot 'MTV type' music videos often filled a significant portion of the show, and the dance troups were entirely eliminated.
Before music videos, it was common for many recording acts to be 'studio only' bands. Song writers or producers would hire studio musicians to record their song. If it was a hit, actors often unrelated to the recording would appear on
ToTP to mime to the hit song, or a band would be formed to perform the hit song at live gigs.
Tony Burrows famously appeared four times on one episode of
TotP in 1970. He was the lead singer of four different 'studio only' bands who were simultaneously on the UK charts, (Edison Lighthouse, Brotherhood of Man, White Plains and Pipkins). Burrows' voice is best know to North American audiences from the 1974 hit
Beach Baby by First Class.
The vast majority of
ToTP episodes from 1964-75 no longer exist in any form, other than memory. The BBC 'wiped' the videotapes so that they could be used for something else. Many other episodes from the 1960's and 70's are now banned from rebroadcast on the BBC because they were hosted by Jimmy Savile. Allegations of Savile's sexual predation became public news following his death in 2011. It is generally believed that the BBC knew of his sexual abuses for years, but did nothing about it. Similarly, episodes which feature Gary Glitter are no longer part of the rebroadcasts.
I don't know if this is still the case, but about ten years ago, for a few years the BBC aired
TotP episodes from 30 years prior each week. I have quite a few episodes from the late 70's/ early 80's sourced from these rebroadcasts, obtained from a private torrent site named thebox.bz, which had UK television and radio broadcasts for all of its content. thebox became zxcv.bz in 2012, and became defunct in 2014, largely from pressure by Rupert Murdoch, who objected to sports torrents circulating from broadcasts on his pay-per-view Sky television network.
Television viewers in the UK have to pay a monthly fee to see any stations, and much of the money raised funds the BBC. Low income people often could not afford both an Internet connection and a television license, so they would subscribe to an Internet ISP, and download their television from torrents on thebox.
