The article text supplied for this piece consists only of website navigation and header elements, with no actual body content provided beyond the headline question about which song topped the charts when The Beatles announced their split in 1970. As such, no substantive details, quotes, or context from the article can be reliably summarised.

The piece appears to be published by Far Out Magazine and is framed around Paul McCartney's April 1970 announcement that he was leaving The Beatles, which effectively marked the band's break-up, with the article seemingly intended to reveal which song held the number one chart position at that moment. However, the specific song title and any surrounding musical or historical context are not present in the text made available for this summary.