The Rena 616, which cost £10,000, can run at speeds of up to 40,000sph at 600dpi and has a total of six printheads.

Andy Harrison, sales manager at Leeds-based First Class Post, said: "While the company's core business is litho overprint of envelopes, we have recognised the increasing requirement for the add-on services provided by such a piece of kit and have reacted accordingly."

He said there was an expanding market for numbering of envelopes, including postal ballots, automated banking deposit envelopes and receipt wallets.

"The fact that the Rena machines are also capable of bar-coding and personalisation adds further strings to our bow and opens us up to other markets," Harrison added.

"In these economic times, I believe a company of our size needs to offer an expansion of its services."