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Introduction
Careful owners
A complete rebuild
Old boiler

The steam plough is completely dismantled and stacked up in the corner of a yard in Somerset when the Salvage Squad first see it. They have six months to get it working again.

Fowler Steam Ploughing Engine No 1368 – nicknamed 'Margaret' – was built in 1870 and is one of the oldest surviving engines in the world. Steam ploughs were a major innovation: whereas a pair of horses could only plough an acre in a day, a team of five men with two ploughing engines could easily complete 15 acres. Two engines would pull a plough across a field using a long cable and winch fitted under the boiler. This system was common from the 1860s until the Second World War, when tractors took over.

Margaret worked continuously for 74 years and was then laid up until 1963 when she was bought by the Tame brothers, steam enthusiasts from Didcot in Oxfordshire. They restored her and kept her until 1980 when declining health meant that she had to be sold.

Andy Melrose (the steam expert who helped the Salvage Squad to restore the steamroller 'Hercules' in the first series) first saw Margaret at a steam rally when he was 15. She caught his eye because she was the oldest machine there: 'I sort of fell in love with her but I never thought that one day I would own her.'

Andy purchased Margaret in 1980 and did a lot of mechanical work on her but 15 years later he became concerned about the state of her boiler. When he dismantled the engine he realised that the firebox and boiler would need to be completely rebuilt. Progress was very slow because Andy spends a lot of time working on other people's engines.

A 130-year-old, 20-tonne ploughing engine in need of a completely new boiler is a serious engineering challenge but, with the help of Andy and his assistant Richard, the Salvage Squad agree to take it on.

The main task is to rebuild the boiler from scratch. The boiler is made of two separate cylinders of 0.5-inch thick steel riveted together. As well as being the 'heart' of the engine, it also acts as the chassis to which all the other pieces are attached, including the winch which can pull the 5-tonne plough at 5mph for up to 550 metres.

Claire and Andy use a massive pair of rollers to roll the two pieces of steel plate to the correct diameter. Axel and Jerry then use the gantry and a huge ratchet to squeeze one cylinder so it will just fit inside the other.

As the boiler is a pressure vessel, it is crucial that the riveting is done perfectly. The boiler needs over 600 rivets, each of which has to withstand a steam pressure of 150 pounds per square inch.

Axel, Claire and Jerry use a squeeze to rivet the tube plate to the boiler. This is a G-clamp powered by compressed air, which squeezes the white-hot rivets together. It's a real team job, with Claire heating and placing the white-hot rivets, Jerry positioning the squeeze and Axel operating the mechanism.

The completed boiler is an impressive site. The Squad are still a long way from ploughing but, with the biggest task under their belt, they meet their six-month deadline in the end.