CMS Cameron McKenna, Nabarro and Olswang have told their business services support teams that all roles are up for grabs at the merged firm, putting around 850 UK-based non fee-earning roles into the spotlight.

The three firms are understood to have communicated to staff last week that they would be assessing the capabilities of each individual and deciding who does what at the new firm.

The news counteracted assumptions Olswang and Nabarro would have to sacrifice their business services teams in favour of CMS Cameron McKenna’s when the firms move into Cannon Place.

Decisions as to who takes on the new senior roles at the combined firm, such as head of business development, head of HR, and IT director, are expected to be made before the end of October.

The three-way merger will see a significant overlap in its respective business services functions and current figures suggest more than 500 roles could be at stake.

Olswang currently has the smallest non fee-earning staff headcount at 263. Nabarro has 313 staff and CMS has 269 staff in the UK out of 1,730 staff globally.

Law firm business services functions are typically the most heavily hit when mergers take place, with lawyers’ roles more secure in the short term. Olswang and Nabarro partners are already understood to have signed six-month lock ins, while CMS Cameron McKenna partners are thought to have been exempt from tying themselves to the merged firm before the go-live date.

Following its last merger with Scotland’s Dundas & Wilson in 2014, CMS axed 60 business services roles in one go due to overlapping responsibilities.

A spokesperson for CMS UK at the time said: “With any combination it is regrettably to be expected that there are some duplication of roles resulting in redundancy.”

The combined firm will also be looking to implement major efficiencies as it launches a lengthy and expensive integration process, which will also see it attempt to divest significant rental liabilities at Olswang and Nabarro’s current offices, which could lead to a further reduction in headcount.

A number of UK firms have been cutting support staff this year. DLA Piper axed 180 UK roles in September ahead in a bid to relocate support roles to Warsaw; Norton Rose Fulbright is currently relocating 170 global roles to its new support hub in Manila; and Dentons will lose 50 UK jobs, as it also opens a low-cost base in Warsaw.