The 1971 postal strike meant data had to be collected by telephone, but this was deemed inadequate for a national chart; by 1973, the BMRB was using motorcycle couriers to collect sales figures.In May 1978, the singles chart was expanded from a Top 50 to a Top 75.The most widely circulated chart was the NME one, as used by Radio Luxembourg's legendary Sunday night Top 20 show, as well as by ABC TV's Thank Your Lucky Stars, which had an audience of up to 6 million on ITV. The sampling cost approximately £52,000; shops were randomly chosen from a pool of approximately 6,000, and submitted figures for sales taken up to the close of trade on Saturday.The sales diaries were translated into punch cards so the data could be interpreted by a computer.Readers followed the charts in various periodicals and, during this time, the BBC used aggregated results of charts from the NME, Melody Maker, Disc and (later) Record Mirror to compile the Pick of the Pops chart.
(publisher of Music Week), in cooperation with the BBC and the British Association of Record Dealers (BARD) – representing retailers, including W H Smith, Woolworths, HMV and Virgin – who agreed to exclusively supply sales data to the CIN.
The UK Singles Chart (currently entitled Official Singles Chart) is compiled by the Official Charts Company (OCC), on behalf of the British record industry, listing the top-selling singles in the United Kingdom, based upon physical sales, paid-for downloads and streaming.
To be eligible for the chart, a single is currently defined by the Official Charts Company (OCC) as either a 'single bundle' having no more than four tracks and not lasting longer than 25 minutes or one digital audio track not longer than 15 minutes with a minimum sale price of 40 pence. Some media outlets only list the Top 40 (such as the BBC) or the Top 75 (such as Music Week magazine) of this list.
Once people are signed up, it costs £9.99 (or £19.99 for the "Hi Fi" service) a month.
Tidal is also the only place online you can listen to Prince’s back catalogue.