Thanks George
Perhaps these extracts from other photos are more revealing

There are dark streaks on the crown, but on the back of the crown. 
Other features which indicate Black-headed are the reddish rump, relatively weak streaking on the back, dark outlines around the head markings and longish primary extension.
I'd love to be proved wrong but I think it's a Black-headed.
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 Last edited by wgeoff at 24/12/2009 18:15 ]