Barney was roaming a back alley where he found the Doctor rummaging around in rubbish for clothes. Barney was taken aback by the highly erratic behaviour of the Doctor as he suffered from post-regenerative trauma. Barney tried to play along with the Doctor's whims. He recoiled at the sight of the Doctor's face and claimed not to like it and steered clear of him as best as he could.
The Doctor decided that because he was cold, Barney should give him his coat, though Barney himself was cold. Barney refused to do so until finally being offered something of greater value. He swapped the Doctor his coat for his favourite watch, along with a set of worn out fingerless knit gloves. (TV: Deep Breath)