BILL CRIDER'S POP CULTURE MAGAZINE
I read "Kiss Her Goodbye" and enjoyed it. Last week I ran across Duane Swierczynski's blog at http://secretdead.blogspot.com/ and, he regularly calls calls Guthrie "Sunshine". I assume Sunshine is a nickname and not used as one of those derogatory Limey names.
I think Guthrie is just full of joy, hence the nickname.