The framework of the book is Ó Briain's tour around England (with short excursions elsewhere, particularly to Dublin but memorably also to Jersey), with anecdotes of his interactions with the crowd on each show and reflections on local history and various aspects of Englishness, including race and diversity . There is also a rather moving conversation with Ken Dodd (the inventor of the tickling stick referenced in the title). His main conclusion is that the English actually rather like being gloomy; that England / the UK is fairly consistently about fifth in everything, but mourns not being top. Tho that he adds that the English have a peculiar paranoia about their young people (ASBOs, etc), and some very trenchant observations about the differences between England and Ireland (the contrast between St George's Day and St Patrick's Day is particularly telling).
Looking at on-line reviews I see several who are baffled because they don't get the Irish bit (some of whom are even more baffled because they don't know much about England and had hoped in vain to learn the basics here). I see others who know Ó Briain's work too well and are disappointed that the book reflects his stage show too closely. Fortunately I am in neither category and thoroughly enjoyed it. Paxman's book is probably better (and Bryson's certainly worse) but this is the most fun.