Diesel in a petrol- short urgent advice please

[agoogy]

On behalf of my 'old man'...whose just emptied 40 litres of petrol from jerry cans into his Cooper....he's since discovered one of the jerry cans will have had a no more than half a pint of diesel dregs in it....
Its running, sometimes smoothly, sometimes jerky, some white smoke not alot but some... what does he do? and how does he do it?

thanks

[agoogy]

Thats what he's doing, but his ileage is low... I've heard the fule tank has a 'bung' in it...could this allow a quicker fuel drain? and if so is it easy to describe where I find it?

thanks