Reviewed by Julia LangdonHEAD OF ZEUS, 352pp, £12.99Tablet bookshop price £11.70              Tel 01420 592974 There is a curiosity to this political thriller which first strikes the unsuspecting reader on page 7, when our hero, Will Flemyng, a Foreign Office minister, makes for “the phone box on the next corner”, assembles a pile of coins, and rings his brother. “Eh?” I thought. “Minister? Phone box?” I had failed to read the front flap to the cover, which places this first novel, by one of Britain’s best-known broadcasters, in the mid 1970s. Having absorbed this shift back in time, I read on, intrigued why such a conceit was necessary. Would it have something to do wit