The Marquis de Carabas

"The Marquis de Carabas is a little bit roguish in the way that Rats are a little bit furry", is one description that was given of this curious denizen of London Below.
He appears to be regarded as a person who can make things happen or find almost anything - for a price, and while not entirely trustworthy his skills are worth the risks of dealing with him.
In return for his aid while Mrs MacTannon, Belladonna, Garvin and Rig encountered London Below he demanded a favour, to be redeemed at a later date.