The phenomenon is caused by a regular rainbow and a sunset happening at the same time.
Pink rainbows spotted over south and west of England
Rare 'pink rainbow' spotted in sky over Bristol
Rainbow - Wikipedia
Rainbow clouds spotted in the East for first time since 2016 - BBC
A rare pink rainbow was spotted in the sky over Bristol, England
Lightning rainbows Rare double 'lightning rainbows' illuminate UK
Sun halos, arcs and upside-down rainbows seen across England
Pink rainbows seen at sunset - BBC Weather
Rare pink rainbow spotted in the skies over Devon - Devon Live
Pink sky: Why did the clouds above Wales change colour? - BBC News
A rare pink rainbow was spotted in the sky over Bristol, England