By June 1940, the numbers employed there had risen to nearly 15,000. At its wartime peak, ROF Chorley had over 28,000 employees – a staggering figure at a time when there were only around a dozen factories in the whole of Britain with a workforce each of more than 19,000 people (four of these being the Royal Arsenal, ROF Bishopton, ROF Chorley and ROF Bridgend). ROF Chorley was the site where the bouncing bombs, designed by Barnes Wallis and famed for the " Dambusters raid", were filled, the main site for the filling of large-capacity aircraft bombs being ROF Glascoed.