This pair of gates are very old, manufactured before electricity was commonly
available. This can be seen in the fact that they are of riveted construction as opposed to being welded by either electric or gas. They would have been made by a blacksmith in a forge using lengths of flat bar that had been rolled as they were cast in a steel foundry. These flat bars would have been heated in the forge and cut to length on an anvil using a hammer and chisel. They were then heated again and holes punched where joins needed to be made. The joins were made by lining up the holes and pushing a piece of red hot metal through them which was then hammered flat at both ends on the anvil so that the rivet could not move either way and the bars were permanently joined.
The crossbars of each gate are closer together at the bottom than at the top, which is common in the design of field gates to this day. This design makes no difference to large animals like cattle or horses, but facilitates the containment of smaller animals like sheep.
The vertical and horizontal bars form the basic gate but there is also an inverted V and a short vertical in each gate to provide some reinforcement to the longer horizontal bars to avoid flexing and give stability.
Modern gates would span the gap with a single gate, but then they are manufactured in huge workshops where the length of the steel is not an issue. The blacksmith who made these gates was probably working in a small workshop and had to work with shorter lengths of steel to facilitate access to his forge and anvil.
These particular gates are also interesting in that they bolt into each other. It would be more usual for one gate to have a sliding drop pin which secures it in place to the ground. The second gate would then have a single sliding bolt which secures it to the other gate. The sliding bolts here give two last indications of the blacksmith. Their vertical mounts have been twisted and this would have required heating in the forge, and also the flat bars have been heated and hammered into round pins at the end to allow them to slide into punched holes in the flat bar of the other gates.