Great Northern Railway petrol railcar at Hatfield, Hertfordshire, when working the service to Hertford. in 1904 two railcars, Nos 3&4, were built by outside contractors. They were equipped with 2 four cylinder Daimler engines and were handsome but hard-riding 4-wheeled vehicles with a driving compartment at either end. The open passenger compartment had tip-over seats and a trapdoor in between gave access to the engines and central gearbox. The first tests weremade between Hatfield and Hertford and the cars were eventually put into service on the line for some months. The engines gave little trouble but the gearboxes were a constant anxiety and the pawls broke with monotonous regularity. Another difficulty was that the engines had to be started by hand and a strong one at that. The service was only maintained at the expense of many sleepless nights spent on repairs and the experiment was eventually dropped.