'Is it or isn't it'..........

I didn't feel like venturing far yesterday so popped down to Parc Slip NR hoping to catch up with the wintering Water Rail using the overgrown pond behind the visitor centre.
The rail only showed fleetingly but what took my eye was a small pale Chiffchaff moving around the reeds and trees, it was predominantly brown with a very clean white underside and just a hint of olive in the wings, when it called it gave out a very sharp 'peep'.
It is the same bird photographed by Tony Swann the previous day and he thought it was a good candidate for the Siberian race 'Tristis', I agree, what do you think ?