The company said the investment was a response to a growth in turnover, which it said had grown to  £5.4m for the first six months of the year, up 50% from £3.6m in the same period in 2008.

According to managing director David Laybourne, a large amount of the additional turnover has been created by one-piece mailers and the investment was made in order to "bolster" its capacity.

The machines, which is the the fourth Heidelberg mailer the Croydon-based company has bought, was installed last Tuesday (28 July).

Laybourne said: "This investment allows us to do a lot, we have been bringing in new business and it gives us the capacity to continue this aggressive growth strategy.

"One customer that began working with us three years ago on an initial 70,000 run campaign is now doing 1.9m, while another that started a loyalty campaign with us this year has got 2.5 times more responses than it expected. I believe that is down to the service we are able to offer."

Real Digital's Stahlfolder was installed with round pile feed. It is capable of handling sheets of up to 660 x 1,280mm.

Laybourne added that the modular nature of the machine, and its other Heidelberg lines, allows the company to create bespoke lines depending on each job.