unknown goose (hybrid?)

unknown goose (hybrid?)

Observation - unknown goose (hybrid?) - UK and Ireland. Description: This was a lone bird in the distance and quite far away from me and all of the other ducks and avocets etc. Even though this is at the coast, all of the birds are in fresh water pools. It looks to have markings of a greylag goose apart from the odd white

This was a lone bird in the distance and quite far away from me and all of the other ducks and avocets etc. Even though this is at the coast, all of the birds are in fresh water pools. It looks to have markings of a greylag goose apart from the odd white markings across its belly and chest. there is a white line across the top of the beak down to its chin like the one on a white fronted goose, however this bird is not a white fronted goose because they do not have any white on their belly's, they also are only winter visitors but I thought it may have been a hybrid that got left behind from the previous winter especially as it's alone and geese are normally in groups. Could it be a white fronted goose hybrid or a greylag and mute swan hybrid? I cant tell if the beak has has a nobble on like a mute swans does. Can anyone confirm my suggestion or give any new ideas for its identification. to add this was on the 31 of july at Gibralta point reserve in 2012 not 2011 as it says by the title. Anything would be greatly appreciated, thank you. the last photo of it sitting down, looks odd as the brownish block is its tail and the white beside it is the wing tips I think.