Green’s Dictionary of Slang

force the voucher v.

(UK Und.) to perform a specific swindle, whereby a ‘firm’ offers to place ‘guaranteed winning’ bets for a victim who has to forward the money in advance; the firm has, of course, vanished when it is time to pay off.

[UK]Sl. Dict. 167: Force the voucher a term in use among sporting tricksters, who advertise to send certain winners, and on receipt of letters enclose vouchers similar to those sent out by respectable commission agents, but with double or treble the current odds marked thereon, in reference to the horse named. A plausible letter is sent with the voucher, and the victim is informed that on account of early investments made by the firm, which has of course a high-sounding title, the extra odds can be laid by them, and a remittance to the amount named, or part of it, is requested. Of course the firm ‘dries up’ when claims become heavy, and, with a new name and new address, appears in the next week’s advertising columns.