Each song is ranked by:
a) Peak Position reached
b) Number of weeks at its peak Position
c) Number of weeks placed in the Top 10
d) Number of weeks placed in the Top 40
e) Number of weeks in total Chart Run.
If, at this point, there is a tie, the order is based on the next highest position(s) reached. Finally any remaining ties are sorted alphabetically by title, then artist.
Singles with two A-Sides that both chart together will have the most prominent side, if applicable, sorted first.
Songs that crossover into the next year are normally included in the year of peak position. Re-entries within 6 months of any previous entry are combined in the one Chart Run. In rare cases when a song moves in and out of the chart over multiple years, with little off-chart time, a serial number is allocated for each year.
1952-1960 New Musical Express (NME)
From 10 March 1960 the Record Retailer (RR) Chart replaced the NME Chart. Songs that crossover are combined into one continuous chart run.
From January 1970 until 1983 the charts were produced by BMRB (British Market Research Bureau) and were used by both the BBC and Record Retailer, (which became Record & Tape Retailer in 1971 then Music Week in 1972).
From 8 Jan 1983 until 1994 Gallup took over Chart compilation from BMRB.
From 12 Feb 1994, and currently, UK Charts are compiled by Millward Brown.