He had assisted in fitting up the gas machinery at the mills of Phillips & Lee, Manchester, as well as at Lodge's Mill, Sowerby Bridge, near Halifax.
He was afterwards employed to fix the apparatus at the Catholic College of Stoneyhurst, in Lancashire, at the manufactory of Mr.Harris at Coventry, and at other places.

In 1813 the London and Westminster Gas Company secured the services of Mr.Clegg, and from that time forwards their career was one of prosperity.

In 1814 Westminster Bridge was first lighted with gas, and shortly after the streets of St.
Margaret's, Westminster.

Crowds of people followed the lamplighter on his rounds to watch the sudden effect of his flame applied to the invisible stream of gas which issued from the burner.

The lamplighters became so disgusted with the new light that they struck work, and Clegg himself had for a time to act as lamplighter.
The advantages of the new light, however, soon became generally recognised, and gas companies were established in most of the large towns.