trainer was to be configured to perform various forms of training, being suitable for both day and night operations, featuring both guns and bombs for armament training, a glider-towing capability, and a general design that would be compatible with navalisation measures, such as a strengthened undercarriage and the fitting of arrestor gear. Within a month of the specification's issuing, Boulton Paul Aircraft had opted to produce multiple proposals in response, as large orders had been anticipated. Boulton Paul's P.108 proposal, which would become the Balliol, was that of a conventional low-wing monoplane, featuring retractable main undercarriage and a fixed tailwheel. Towards the end of August 1945, Boulton Paul received an order from the Air Ministry, calling for the production of a batch of four prototypes, which were to be powered by the Rolls-Royce Dart turboprop engine. During August 1946, this was followed by a larger order for 20 pre-production aircraft, with ten each to be powered by the Dart and the Armstrong Siddeley Mamba turboprop, with delays to development of the Dart meaning that the prototypes would now be fitted by the Mamba. Competing proposals from other manufacturers were also submitted, including Avro's Athena in particular. Into flight As the Mamba was not flight-ready at the time of the first prototype's completion, it was instead powered by a Bristol Mercury 30 radial engine during its initial test flights. Thus powered, it first flew on 30 May 1947, after teething issues with the undercarriage had been resolved during ground testing. The second prototype, powered by the intended Mamba engine, first flew on 17 May 1948, becoming the world's first single-engined turboprop aircraft to fly. Early handling trials at MOD Boscombe Down revealed the aircraft to possess relatively gentle and easy flight characteristics across all typical circumstances, with only minor suggestions for improvements being produced, such as the lack of a port-side walkway and directional snaking unbecoming to a gun platform. Meanwhile, the Air Ministry had second thoughts about its training requirements thus, in 1947, it issued a new specification, T.14/47, requiring a two-seat trainer that was powered by a Rolls-Royce Merlin piston engine. This engine which was available in large numbers from surplus stocks leftover from the war, rather than expensive turboprops that would have to bought in new. On 10 July 1948, the first Merlin-powered Balliol, designated Balliol T.2, performed its first flight. The observer's seat of the Mk 1