This ad from the October 1957 issue of The Motor espouses its virtues

Although the name makes it sound somewhat dangerous, it was in fact one of a number of devices produced at the time to improve fuel economy and performance of petrol engines. The principle behind the Ridley Bomb was water injection into the combustion chamber, cooling the intake charge, which in turn improved volumetric efficiency. It also reduced the tendency to knock, which was useful back in the 50s when poor quality fuel was common.

A test conducted by Motor Sport magazine in January 1956 showed it did appear to work:


In response to the requests of many readers regarding the merits of petrol economisers, a test was carried out on the water injection bomb manufactured by Messrs. Stanley Lipscombe, of Boveney, Windsor. at a cost of £5 10s. The car used for test was a 1951 Ford Pilot with 59,000 miles to its credit, the increase in economy being approximately 10 per cent, on the initial trial run without any experimental alterations to the amount of water being added. The increase in performance was not at first noticed, but after some weeks the engine seemed to run more smoothly and pick up faster. Larger increases in economy are claimed by the manufacturers when the bombs are used on new engines, and interesting effects on carbon dispersion have been noted.



Another example of how perceptions of motoring safety have changed over the years. This came from The Autocar, April 1957


Rather a simplistic view of a “safe anchorage” perhaps, although maybe marginally better than being propped up between Mum and Dad on the front seat of the MkII Zephyr.