Though only eight in number (afterwards increased to twelve) these runners exerted a preponderating influence, which largely altered the aspect of the contest between the professional thieves and the helpless public on whom they preyed. The Bow Street policemen were the first peace officers to make a serious study of the art of detecting and running down criminals: they were experts whereas all their predecessors had been amateurs; no longer dull officials performing routine duties in perfunctory fashion when "not otherwise engaged"; but keen hunters with all their faculties stimulated by the prospect of the blood money and other rewards they hoped to earn. When they appeared on the scene the professional depredator no longer had things all his own way; instead of the parish constable who could be outwitted and bamboozled at every turn, the cracksman or forger found himself confronted by a wary adversary, well armed, and up to every move on the board. That the Bow Street Runners achieved much good in breaking up predatory gangs, and in bringing notorious offenders to trial, is not to be denied, but it is no less certain that they were the source of much evil. Actuated by the hope of gain rather than by any sense of duty, their motives were as ignoble as their methods were shady. They played only for their own hand, and all their best endeavours were bent towards the arrest of the particular criminal whose conviction would bring the greatest profit to themselves, and not to the pursuit of the fugitive from justice whose capture was chiefly desirable on public grounds. Prevention did not enter at all into their conception of police duty, and their services were of course only at the disposal of those who were rich enough to pay handsomely for the privilege. The extent to which this system of feeing was carried may be guessed from the fact that Townsend left £20,000 behind him, and that Sayer's heirs divided no less than £30,000 at the death of their benefactor. In order to obtain information, the runners made it a rule to frequent low "flash-houses," as the resorts of thieves were called, and to associate with the vicious and desperate characters to be found there. When examined before a Parliamentary Commission, several of these officers freely admitted that it was by the employment of such tactics that they expected to obtain the most valuable information, and gave it as their opinion that flash-houses ought to be encouraged rather than suppressed, on account of the facilities they afforded the runner in his search for a man who was "wanted."