Dog and pony show

I've never heard this phrase in the UK. What does it mean?

It means to put on a presentation, usually done by a corporation to bring attention to itself or one of it's products.
I dont know the derivation of the phrase but I would guess it is from a circus. Here in the US in a three ring circus there is always the act that has the ponies parading in a circle going clockwise while there are little dogs jumping from horse to horse in a counter clockwise motion. Just a guess!

I've grown up with this expression. It can refer to any type of presentation or act but sometimes has a derogatory implication to mean that the presentation had no substance just a shallow and cheap entertainment or cheap thrill.