Three contractors are bidding to fix a broken wall at 10 Downing Street; one from London, another from Bristol, and the third from Liverpool.
They go with a government official to examine the wall.
The London contractor takes out a tape measure and does some measuring, then works some figures with a pencil.
'Well', he says, 'I figure the job will cost about £900: £400 for materials, £400 for my crew and £100 profit for me.'
The Bristol contractor also does some measuring and figuring, and then says, 'I can do this job for £700: £300 for materials, £300 for my crew and £100 profit for me.'
The Liverpool contractor doesn't measure or figure but leans over to the Government official and whispers, "£2,700."
The official, incredulous, says, 'You didn't even measure like the other guys! How did you come up with such a high figure?'
The Liverpool contractor whispers back, '£1000 for me, £1000 for you, and we hire the guy from Bristol to fix the wall.'