Record producer signed singer when he was 14
Singer and dance duo Jack Ü releeased 'Where Are Ü Now' last year
'Stitches' makes slow climb to Number One after 17 weeks
Song follows on from singer's recent album 'Purpose'
Singer visited the Mayan archaeological site in Tulum this week
Bieber's getting in the Christmas spirit in close-run chart race
Singer has expanded his fanbase by 10% in the past two years
Both acts join Adele on the line-up
Dennis Graham started his career as a drummer in Memphis in 1962
Extra dates in Birmingham and Manchester also added