Insurers have welcomed a new one-million-strong “super-union” into their workplaces, saying they believe their previous good relations with unions will continue.

The Manufacturing Science and Finance Union (MSF) merged on Tuesday with the Amalgamated Electrical and Engineering Union (AEEU).

The new union, whose name is yet to be decided in consultation with members, will be the biggest union at Royal & Sunalliance (RSA), CGNU and Axa.

An RSA spokesman said the company had recently officially recognised both the MSF and another union, Unifi.

CGNU said it recognised two unions, the MSF and the CGNU Staff Association.