on either side of the vehicle, and the sparks they threw during operation are easily visible on test runs. Starting in the 1970s, construction of test track started in the fens at Earith in Cambridgeshire, supported by Tracked Hovercraft Ltd offices in Ditton Walk in Cambridge city. The track was about off the ground, running along the earthworks between the Old Bedford River and the Counter Drain just to its north, between Earith and the Denver Sluice. The first long section of the planned long track was laid to Sutton-in-the-Isle. Along the full length it was expected the train would reach . On 7 February 1973 the first test train, Research Test Vehicle 31, or RTV 31, reached on a section, in spite of the short track and a headwind. The test was heavily publicised and shown on BBC news throughout the day. Much of the interest stemmed from rumours that the project was facing imminent cancellation. Aerospace Minister Michael Heseltine sent Michael McNair-Wilson to view the test. Heseltine said in an interview that he believed that the project would not be cancelled. Stiff competition By the time construction started on Tracked Hovercraft's test track, British Rail was well advanced on their plans for the steel-wheeled Advanced Passenger Train (APT). The government found itself in the position of funding two different high-speed train systems whose proponents were quick to point out problems in the competing system. To gain some clarity, they formed an interdepartmental working party that studied several potential inter-city transit solutions on the London–Manchester and London–Glasgow routes. The options included 'buses, Advanced Passenger Train, Tracked Hovercraft, and VTOL and STOL aircraft. Their December 1971 report strongly favoured APT. The arguments eventually settled on the need to build new lines. APT was intended to enter testing in 1973, and enter pay service before the end of the 1970s. In comparison, Tracked Hovercraft would not be ready for real-world testing until the late 1970s, and could not enter service until a completely new set of guideways had been constructed. Arguments in favour of TH included the problem that placing APT on existing lines would simply increase congestion on them, and that its speed was simply too low to compete directly with jet aircraft, unlike the TH. If new lines were going to be laid, TH would cost about £250,000 a mile, compared to the £500,000 spent during the same period