Use ALL the silly putty!

Shut the water off

use dough/clay/plasticine to cover it

Call Mario, he is a plumber

THIS!

Is it metal or PVC?

Silence the rat.

use rope. By tightly coiling rope around the pipe, tamping down each loop with something hard like a piece of wood, you should be able to reduce the flow, and then find appropriate patching materials to make a more permenant solution. It's how we do it on naval vessels (ant that's why it's good to know a real sailor).

i take it by your use of "bloody" that youre a fellow brit.
Most places that can help you will be closed. The likes of screwfix or wickes. maybe homebase at a push will have a rapid setting epoxy resin that you can use, but that doesnt help you tonight.
Me? if you have access to it, i'd just cut off the water suppply until tomorrow.

You guys have all been wonderfully helpful, but I'm afraid it was all a ruse. If you take a look in the bottom-right of the image I posted, you may be able to faintly make out the 5 character giveaway code. Ah well, continue the leaks!