The Speedmaster XL145-6+LX, which has joined a Speedmaster XL 105 and Manroland 900 sheetfed press at the site, will be in full production from next month.
The makeready and running speed, colour quality and overall production control were all key factors in the purchase decision, according to plant manager Dean Naylor.
He said: "We looked at other options but our experience with the existing XL 105 and the performance it has given us over the past six years, coupled with the technological developments on the XL 145, were convincing reasons for going again with Heidelberg. Our experience of Heidelberg's advice, service and support has been first class."
Logistics systems built around the press will deliver pallets of board to and remove finished work away from it. This will allow for an uninterrupted workflow which will also reduce the physical and manual aspect for the operators.
GPI has opted for Inpress Control with the XL 145, which will automate the register and colour control. The press is also specified with Color Assistant Pro, which will allow the firm to calibrate to ensure consistent and repeatable colour.
"Inpress Control will speed up makeready, reduce waste and enhance quality. Quality is something we are able to market and offer to all our customers in the packaging sector," said Naylor.
"We have the added benefit of Color Assistant Pro. Customers value their brand and expect quality and colour as a prerequisite."
The press also features simultaneous wash up and ink pumping, which will reduce its downtime and enhance its throughput.
The company's press operators will undertake training courses at Heidelberg's factory in Wiesloch, Germany and its showroom in Brentford in the next few weeks.
"The reaction from all employees has been 100% positive. This investment gives a great morale boost to the plant," said Naylor.
Earlier this year, GPI bought Benson Group in a $165m (£100m) deal.