Congratulations Phil!
As the proud but poor father of three daughters, I simply have to assume:
A) Traditions are hugely different in the UK--- Father of the groom buys there.
B) A is not true, but you recently hit the lottery, or...
C) A is not true, B is not true, at least in what you hit...instead, you hit the punchbowl prior to the photo session and forgot completely what this whole deal is costing you!
j/k, and congrats!