1. A method of coating a field joint of a pipeline, the method comprising:placing at least one body comprising a thermoplastics material around the field joint;
assembling two or more mould tool elements around the field joint to make a mould tool that defines a mould cavity;
heating the body in the mould cavity around the field joint to effect thermal expansion of the thermoplastics material; and
constraining thermal expansion of the body in the mould cavity to apply elevated pressure between the body and pipe sections joined at the field joint, and then removing the mould tool from around the field joint;
the mould cavity has a first volume;
on being placed around the field joint, the body has a second volume such that the body can fit into the mould cavity; and
the thermoplastics material of the body has a positive coefficient of thermal expansion such that, when heated in the mould cavity, the body would expand from the second volume to a third volume greater than the first volume if such thermal expansion were not constrained.