…or to the book that accompanies the TV series QI, the New Scientist collection of questions and answers, basically any witty collection of scientific or historic trivia.
Just by way of a stocking filler for Dad, he likes books that he can dip into like those. I’m aware they all have series or sequels, so I was looking for something similar but by different authors.
IF your dad likes Freakonomics and it’s sequel, he might like Tim Hartford, the “Underground Economist”
Consider this thread subscribed to, so I can also get tips on similar books. 
These two books are similar to Freakonomics in that they deal with behavioural economics and are fascinating reads.
Predictably Irrational by Dan Ariely
The Logic of Life by Tim Harford
Pushkin, something like those Schott’s Miscellany books might be good. HMV do a rake of books like that, worth checking out their books section. Or how about some straight dope books?
I really enjoyed The Know it All by A.J. Jacobs. It’s arranged around both trivia and investigation, but is an autobiography too. Really entertaining - I had it as my bathroom reader for several months.
My dad likes these kinds of books, too. He liked Malcom Gladwell’s The Tipping Point when I got it for his birthday, so he’s getting *Blink *for Christmas.
*More Sex Is Safer Sex: The Unconventional Wisdom of Economics *
There’s obviously the sequel, SuperFreakonomics. I also thoroughly enjoyed The Drunkard’s Walk: How Randomness Rules Our Lives, by Leonard Mlodinow.
Thanks for all the economics suggestions. I forgot to say that as an ex-banker, he does like a little more of the economics over science. Or at least can understand it a little better 
I might just check out HMV, I’d forgotten about their book selection.
Schott veers a little into Mum’s sense of humour and out of Dad’s. He prefers something very quiet and then he sudden changes his mind and goes for Naked Gun/Blazing Saddles fare.
There is also Nudge by Thaler and Sunstein, but Ariely’s book is more fun, since the Thaler book talks more about policy. Both are better than Freakonomics, if only because they talk about experiments they actually did instead of implying that they did.
It’s spelled Harford and is the same author as the Logic of Life author mentioned later.
The Underground Economist is far, far better than Freakonomics.