The Sun reporting the cancellation
Rumors have been flying with speculation about Barry possibly joining Coldplay at Glastonbury's center stage on June 26th. Now the British press reported that
Barry's appearance has been cancelled...
The last time we heard from Barry's management about the issue, nothing had been confirmed. Still, there is a general anticipation for a surprise appearance among the fan community, but now The Sun (online version dated June 15, 2016) et al. reported that Barry was forced to pull out of it due to family illness.
Here is a quick summary from The Sun which has always been the primary source in this regard.