Update: In the space of 24 hours, Alesha Dixon, Sister Sledge, 5ive and East 17 have all pulled out.
Dixon’s management says “Alesha has no political allegiances either way on this issue”, while a statement from 5ive reads: “When Rich and Scott agreed to play the event they understood that it was a pop concert funded by one of the Brexit organisations and not a political rally.
“As it has come to light that this is more a political rally with entertainment included they have both decided to cancel their involvement. They would like to make it clear that as a band 5ive have no political allegiances or opinions for either side. Their allegiance is first and foremost to their fans.”

Source: www.iq-mag.net