Pre-tax profits surged by 86.5% to £1.3 million at the UK’s largest garden fencing manufacturer as it won a contract to protect Eurotunnel from illegal migrants.

Jacksons Fencing, based in Stowting Common, near Ashford, increased sales by 11.5% to £27.6 million in what it described as “a good trading year in 2015 despite a slow start to the year”.

The firm made 14-metre swing gates for Eurotunnel, weighing 3,200kg and capable of bearing the weight of a double-decker bus.

It took teams four hours to secure the gates and posts in place.

Founded in 1947 by the father and grandfather of chairman and chief executive Peter Jackson, Jackons’ website is the biggest e-commerce fencing manufacturer site on the internet.

It has three fencing centres, at its headquarters in Ashford and in Bath and Chester.

Gross profit increased 9.3% to £8.2 million in the year to the end of September, according to its latest accounts filed at Companies House.

Company secretary Neil Jordan said in his report: “The company has considerable financial resources together with a large customer base spread across different geographic areas and industries.

“As a consequence, the directors believe that the company is well placed to manage its business risks successfully despite the current uncertain economic outlook.”