The major charts at the time were NME, Melody Maker, Disc And Music Echo and Record Retailer, in roughly that order, most recognised first. (The BBC, meanwhile, was using a weird chart compiled by averaging out the first three of these). When Paul Gambaccini and his pals were compiling the first "Guinness Book Of British Hit Singles" in 1977, they opted to use the Record Retailer chart from its inception in March 1960 because it was a top 50, and the others were top 20s and 30s. The snag is, nobody cared much about the RR chart at the time. It was printed in a trade magazine that wasn't even on general sale, and what's more it used a points system rather than adding up actual sales to produce the listing. (i.e. record shops would send in their own best-seller lists, and RR would give, say, 50 points to the number one, 49 to the number two... I don't know the exact scoring system, but that's the principle.) There wasn't a proper official chart until February 1969, when the BBC decided enough was enough, joined forces with Record Retailer, and paid a professional polling firm to do the whole thing properly.