A spokesperson for Marks & Spencer said: "We had five great years working with Unity and remain on good terms. However we are looking at a new approach in 2017 and have identified a shortlist of agencies that we’ll be working with in the coming weeks."
It comes shortly after Unity’s Spark Something Good campaign for M&S was named Campaign of the Year - Techniques at the PRWeek UK Awards in October.
It follows a turbulent period for the retailer. In November, M&S announced it would close 30 stores in the UK and convert 45 more into food-only shops, while also shutting 53 outlets internationally, amid falling profits. The plan is expected to cost £150m over three years.
Earlier this year Steve Rowe, who became chief executive of M&S in May, also announced plans to cut 500 jobs at the company’s London head office and transfer 400 more jobs outside the city.
In a statement to PRWeek, Unity said: "We’re so proud of the work we’ve done together, from launching Shwopping way back in 2012 to our recent Spark Something Good campaign, which won Campaign of the Year at this year’s PRWeek Awards. Needs change, so we’ve parted ways for now, but remain on each others’ Christmas card lists."
Unity wasn't involved in M&S's latest Christmas campaign, which centred on a film created by ad firm RKCR/Y&R.
Retailers' PR changes
M&S is the latest retailer to make significant changes to its PR agency setup in 2016.
In September, PRWeek reported that Asda was to end its contract with Freuds after bringing in a new vice president of corporate affairs, Charlotte Cool.
Shortly afterwards, Co-op Food appointed M&C Saatchi PR on a retained contract for a wide-ranging consumer brief.
In the first half of the year, Lidl appointed W as its first retained PR agency in the UK, while Shine @ The Academy and Cirkle were added to Morrisons’ roster.
Elsewhere, Aldi is currently seeking new PR agencies to potentially add to its roster.