That's interesting, here in the states we have Boddingtons in cans with the widget so it's interesting to hear that it's actually served on Nitro in the UK (I was thinking it was done by a beer engine). Same thing with Old Speckled Hen in the cans over here, they achieve the 'cask pour' with the...

Yep, hitting sort fixed it for me. Tried all the other recommended fixes and that's what did it.