The pair were joined by musicians Marc Almond, Sandie Shaw and Boney M's Liz Mitchell at a parliamentary reception to celebrate the milestone on Tuesday (November 13).
The Official Charts Company hosted the reception in conjunction with the House Of Commons All-Party Parliamentary Group On Music and a number of music industry associations.
Blackburn hosted BBC Radio 1's Official Chart Show between 1979 and 1982, and is also a former host of Top of the Pops.
He currently presents BBC Radio 2's Pick of the Pops, which is the longest-running chart show on British radio or television.
Jamil will take over the Radio 1 Official Chart Show in the New Year, replacing The Voice co-presenter Reggie Yates.
She said last week that she is "absolutely delighted and honoured" to be taking over the programme.
The first singles chart was published in NME on November 14, 1952, and was topped by 'Here in My Heart' by Al Martino.