Before the M25 was finished, a search was held for potential service station sites. The plan was to reserve an infill 'Leatherhead services', and to build full services at Sevenoaks, and at the western side.
Closely spaced junctions and flyovers made finding a suitable site on the western section difficult. It was eventually decided the only option was to build a full service area to the west of J14, which at the time was the exit for a spur road to Heathrow. This was Poyle services, although it later became Colnbrook.
In 1976 a report stated that the alignment and interchange options at Colnbrook still hadn't been settled on. This looked likely to stop the services, but the obstacle must have been overcome, because it was included in the M25 public inquiry as part of the Heathrow junction, and scheduled to be included as part of the motorway's Compulsory Purchase Order in 1977.
Colnbrook services would have been neatly tucked between the motorway and the reservoir, on a 32-acre site. The services would have cut off a path accessing a local park, and although alternatives were considered, this eventually caused Poyle to be dropped as a proposal. With the opening of the M25 moving closer, Iver was analysed.
Meanwhile, Leatherhead was dropped and sites were considered at New Haw and a popular option at Walton-on-the-Hill (Frith Park) which could be "an attractive place to stop". There were two conflicting schools of thought: one being that a scaled-down version of the services would be more politically successful and would be better than nothing, the other being that a small service area would be underworked and a waste of time. Other options included Addlestone Combelands, Rye Wood, Bookham Road and Poynters Farm - the latter being ironically opposite where the private sector eventually built Cobham.