OK I have seen where to buy section markers but where can I get hold of the wire section marker holders that are used to define the route of a section? You know the ones, about a foot or so long with a loop at the top that the marker slides into.

We make our own using "plain" rather than high tensile fencing wire. A jig is made by welding a section of scaffolding tube about 6 inches long onto a piece of angle iron. The angle iron can then be clamped into a vice to hold the jig firm. A slot should then be cut into the top of the tube to slide the wire through to hold it while it is formed around the tube (2 or 3 turns works well). The wires can be made any length for different ground types!