Sam Fender surprised fans at Olivia Dean ‘s O2 Arena concert with a performance of ‘Rein Me In’ – check out footage of the moment below. READ MORE: Olivia Dean live in Glasgow: a new popstar’s victory lap The song originally featured on Fender’s third and latest studio album ‘ People Watching ’, but later took on new life during his  huge London Stadium gig last year, when he brought Dean out in front of the 80,000-strong crowd  and performed a collaborative rendition. The two of them would then join forces twice more at shows to share the duet – both held at  Fender’s huge homecoming shows at Newcastle’s St. James’ Park , and last June, they officially released the track . Since then, it’s become a fan-favourite, winning the BRIT Award for Song Of The Year , and scoring Fender his first ever Number One single .…