It does, but it only works once - and the value has changed.
Go to the private_items folder in the game director, open up the house.txt file and change the following item:
Large Estate,Grand domaine,Luxusvilla,Propiedad grande,Grossa tenuta,Duża posiadłość,7000000,largeestate.bmp,2005
to
Large Estate,Grand domaine,Luxusvilla,Propiedad grande,Grossa tenuta,Duża posiadłość,-10000000000000000,largeestate.bmp,2005
It may look weird when copied and pasted, the - might appear on one line with the money value on another - but don't worry. Just save the file, go into the private items screen in game (can edit the file with game already loaded!) and buy the Large Estate, which should have a value of -£5t or something.
Yes, that's TRILLION.
Buy it and that's the bank balance you'll have! More than enough to do whatever you want!
It MIGHT only work with a ZERO bank balance as soon as you start a new game. I'm not sure. What I do know is that follow the above and it DOES work - but you can only buy ONE of the item, no more and it doesn't work if you set multiple items to the value and try to buy those.