David Cooper very kindly sent me this link to a juvenile Eastern Common Crossbill trapped and ringed on Fair Isle in June 2005
See here
http://www.fairislebirdobs.co.uk/Sightings/2005/jun_2005.htm
This illustrates the variability in the size of Common Crossbill bills and the Sussex female is very similar in proportions and forehead shape
See
http://www.wildbirdgallery.com/images/birds/loxia_pytyopsittacus/pytyopsittacus.htm
A portfolio of Scandinavian Parrot Crossbills for comparison