The Brentford-based firm was placed 45th in the list and was ranked as the sixth greenest manufacturer.

Managing director Mike Freely said: "Our industry can be very wasteful and we were once part of that, putting some 200 tonnes of plastic into landfill per year.

"However, we have turned that on its head and now 65% of our wastage is recycled."

As part of its aim to achieve ISO 14001, the company has introduced a recover, recycle and re-use scheme and now recycles 65% of its waste.

The Best Green Companies survey uses employees’ ratings of a firm’s green credentials, as well as an assessment of its environmental performance, policies and practices.

Allsignsgroup staff gave the business green scores of 99% and 96% respectively for knowing where to put waste and what waste goes where.

The methodology for the survey was devised by The Sunday Times in conjunction with global environmental consultancy Bureau Veritas and research firm Munro Global.

The 60 companies in this survey are all pioneers – enterprising, enlightened and fizzing with new ideas, said The Sunday Times managing editor Richard Caseby.

The Sunday Times Green List was published on 24 May.