I'd like to contact John Colley, a freelance motor photographer
who may be based in Derby, England.  He specializes in Porsches if
that helps.

Hello bugbear,

Thank you for your question.

Had to search a bit and found quite a few wonderful examples of his
work. Noting that some were attributed to "John Colley Photography", I
searched the UK Yellow Pages at Yell.com and located the information
for his business that you desire:

http://www.yell.com/search/DoSearch?state=INI&screen=VAL&targetName=&businessType=&companyName=john+colley+photography&location=&Submit.x=44&Submit.y=3

John Colley Photography 
Old Hall Farmhouse, The Green Brailsford 
Ashbourne Derbyshire 
DE6 3BX 

Tel: 01335 361255 

I trust this will be the contact information you require.

If a link above should fail to work or anything require further
explanation or research, please do post a Request for Clarification
prior to rating the answer and closing the question and I will be
pleased to assist further.

Regards,

-=clouseau=-

Good work; that's him.

Happy to help.

Thanks for the rating and tip.

Regards,

-=clouseau=-