Golden Oriole along the Thames?

I was on a very early morning bikeride along the Thames yesterday morning very close to Kew Gardens, thick with wood,and and a bird slightly bigger than a blackbird flew out from the bank of the river. What caught my eye was a very definite yellow between its wings as it flew. The rest of the body was blackbird coloured and it wasn't a small bird. It really struck me as something unusual and I have spent ages trying to understand what it could be! I considered a yellowhammer but they are too small and trying to follow the rspb test led to either to water birds or finches. That flash of yellow was so strong. It wasn't close to resembling a woodpecker in shape or indeed a kingfisher with its yellow. It seems that I may have been lucky enough to have spotted a Golden Oriole!! Have any other sightings been made in that area?