As the M6 continued north towards the Scottish border, planners were becoming increasingly concerned that the traffic levels would be so low that nobody would want to build any service stations. With breakdowns and driver tiredness being big concerns, the services were needed, it's just that they wouldn't be selling the thousands of meals that their southern counterparts were.
Clifton services was one of those, where predicted traffic levels were so low that there wasn't enough interest to take it off the drawing board.
Some documents suggest the services would have been southbound only, like Killington Lake. This would match the ghost slips, which are only visible on the southbound side - but the highway boundary (the fencing around the motorway) seems to have left room for a northbound onslip to be built too. There may have been a car park on this side only.
The large plot of land reserved for it is very flat and would not have required much work. Between the onslip and the offslip, there appears to be a tunnel under the motorway, although it looks like it is now fenced off.
The services would have been twice as big as the nearby village of Clifton. Planners were slightly surprised to discover the residents, some of whom backed on to the services, were indifferent about the idea. Lord Longsdale had his land split in two by the project which could have had expensive consequences.
The nearest services - Tebay and Southwaite - are almost exactly 15 miles away each side. Both of those were also expected to be quiet, and over time these two have been grown instead of having a third service area.
A police outstation was planned to be provided here.