Mallard/muscovy mix?
Domestic muscovy x domestic mallard,
giving a good shelduck imitation with these white amd pale grey areas...
Many thanks again for the replies. Probably quite a mixture then. Would love to see it's family tree!
John,
The family tree would only contain Muscovy and Mallard, albeit domestic varieties of each. All the other guesses were wrong, as pronounced by Joern, who is a true expert on hybrid wildfowl (with due respect to Quercus and Hotspur who also got it right)
Graham
Well, this is a cross that can be tricky due to the variation in the many domestic duck races especially in domestic mallard duck, but there are also quite a lot of odd colour forms in domestic muscovy.
In the following link you find mainly photos and links to wild coloured hybrids Mallard x Muscovy, but also to some mainly white hybrids, clearly involving domestic forms from both sides:
http://www.flickr.com/groups/hybridbirds/discuss/72157602472617276/