Client wins for the company, the UK’s second largest postal operator with a turnover of more than £600m, include a 37-million-items-per-year contract for mailing house OTM Opus Trust Marketing, which was previously held by Secured Mail.

Whistl has also won a 20-million-items-per-year contract for Dixons Carphone Warehouse, which was previously held jointly by UK Mail and Secured Mail, as well as a QVC contract from Royal Mail.

One of the most significant new wins is a seven-year deal with Edinburgh based Aegon, to collect, sort and transport 10 million items of mail a year. Whistl said it believes this is the longest contract in the history of the deregulated postal market.

“Whistl has gone from strength to strength in Scotland since we opened our first depot 10 years ago,” said chief executive Nick Wells.

“The securing of an unprecedented seven-year deal with a key client reflects on the professionalism of our team and trust the client has in us to deliver a high-quality service.”

Additionally, Sky, Whistl’s launch client in 2004, has renewed its contract and the AA has retained Whistl for its mailing activity.

Other renewals include Cotton Traders, Direct Wines, Synertec, Royal Sun Alliance, Swinton Insurance, Standard Life, on a five-year contract, and Allied Irish Bank.

Hillary’s Blinds, M&Co Stores, charity Macmillan and print management company Webmart have also renewed their contracts.

“The range of new client wins and contract renewals we have secured reinforces Whistl’s strength in the postal market,” said Wells.

“We are committed to providing the best client service in the sector and our collaborative way of working with existing and new clients delivers efficiency and cost savings for them and improved service for their customers.”

In December the company appointed home delivery specialist Christine Key as director of its Packets and Parcels arm to help grow the division and build its volume and client base.

Key joined the Whistl executive board, which was formed following the recent MBO of the company from PostNL and also saw the firm appoint James Greenbury as a senior independent director in November.

Prior to the MBO, Marlow, Buckinghamshire-headquartered Whistl had been a wholly owned subsidiary of PostNL since 2011. It was previously called TNT Post UK, prior to a rebrand in September 2014, and had been a subsidiary of TNT Group until 2011.