Hi Phil,
 
Barring Canadas, the odds are that any big flocks of geese flying over at this time of year are going to be Pinks. Of course it's sometimes hard to judge size when there's nothing to compare against but Pinks really are quite small. They're also noticeably short-necked and with good views the dark head contrasts obviously with the paler body and front part of wings. The call is a good pointer too - a yack-yacking sound, very different from Canada or Greylag.
 
I suppose there's Bean and White-fronted to think about too, but a big flock of either of these is extremely unlikely.  
 
Then again, 37 Barnacles were photographed at Lighthazzles Res the other day, which shows that anything's possible. Wouldn't have minded seeing them! 

I was at Royd Moor yesterday afternoon, where a dog walker with bins told me he had seen about 30 Barnacle Geese here the " other day", possibly the same birds.
 
Nick

Although their voice has already been mentioned, I would describe it like a vintage car sound. Once learned you will pick the sound up often a long time before you see the goose flock and especially on cloudy days when they could well be above the cloud base.  
 
This Thursday looks a good possibilty with clear/sunny skies forecast and a Northerly wind, to assist them flying South from Iceland.
 
Regards,
Steve