Some absurdly low guesses in this thread 
Imagine a stack of 10 £1 coins. Then imagine 10 stacks of 10 £10 coins. You can fit that on a beer mat - that's £100. How many of those can fit in a pint glass? Then how many pint glasses fit in a 4 pint pitcher overfilled?
To be honest, my £1,800 guess is probably far too low as well.

Imagine a stack of 10 £1 coins. Then imagine 10 stacks of 10 £10 coins. You can fit that on a beer mat - that's £100. How many of those can fit in a pint glass? Then how many pint glasses fit in a 4 pint pitcher overfilled?
To be honest, my £1,800 guess is probably far too low as well.