The Cambridge Guided Busway opened in 2011 and runs from Huntingdon to Cambridge along the route of the old railway line.
There are Park and Ride sites at both St Ives and Longstanton. St Ives has a number of pubs and cafes, but there is nothing at the Longstanton end, I'm afraid, other than a bus shelter to sit and eat your sandwiches in.
The route runs for 25 kilometres with a public bridleway alongside it. The bridleway passes through the RSPB reserve at Fen Drayton Lakes If you enter the reserve, please keep to the marked pathways at all times.
Further information about the Cambridge Guided Busway and a map of the route can be obtained from the Cambridgeshire Local Government website or Wikipedia
NOTE: You will need a piece of wire or a stick to retrieve this one.