In 1955 Morgan Giles received an order from the Ministry of Supply to build two 43ft Range Safety Launches for the RAF designated 1659 and 1660. Delivered in 1956 these were designed by JI Thornycroft. In addition to range work they were also used as seaplane tenders. Morgan Giles were one of six builders contracted to produce these boats in addition to Thorneycroft's.
Each had a loaded displacement of 12 Tons and were powered by two Rolls Royce supercharged diesels of 260HP enabling these craft to achieve 20 knots and a range of 200 miles.