Allen's plan consisted in a system of vouchers and what he called post-bills, by means of which the postmasters might act as a check upon each other. The post-bill which accompanied the letters throughout their course was designed to distinguish the bye-letters from others, and to shew the total amount of postage to be collected; the voucher appears to have been nothing more than the acknowledgment which each postmaster gave of the amount to be collected by himself; and these two documents were sent periodically, once a month or once a quarter, to Allen's office in Bath, where they underwent a rigid scrutiny. Simple as this check was, it was only by ceaseless vigilance on Allen's part that he could get it carried out. To make in the post-bills entries which should have been made in the vouchers, to omit to send the vouchers to headquarters, to confound the bye-letters with the London and country letters--these were only some of the devices to which recourse was had in order to defeat the check.
Allen was better qualified probably than any other man living for the task he had set himself to perform. Of a temper which nothing could ruffle, with ample means at his command, and accountable to no one but himself for their disposal, and possessed of an amount of local knowledge which even at the present day is perhaps unrivalled, he enjoyed a combination of advantages which might have been sought elsewhere in vain. His patience indeed was inexhaustible. No subterfuge, not even a transparent attempt at imposition, would call forth more than a passing rebuke. "'Tis faulty," he would write, "'tis blameable"; and then, perhaps, from the following words would peep out, in spite of himself, a gleam of merriment at the clumsiness of the contrivance.
To a man of less easy temperament even the conditions under which he worked would have been intolerable. Under the terms of his contract Allen's surveyors were to be the officers of the postmasters-general, and to do as the postmasters-general bid them. This was no mere nominal condition. When Allen wanted something done, it may be in the extreme north or the extreme west of England, he might find that the surveyor whose business it would have been to do it had been summoned to London to wait upon the postmasters-general in Lombard Street. Hardly less provoking must have been the condition that the surveyors, though Allen's servants, were not to receive from him any instructions which the postmasters-general had not first approved. Ordinarily Allen was at Bath, and it was there that the instructions were prepared; yet they had to be sent to London for approval, and were seldom despatched thence to their destination until seven or eight days after the dates they bore.
