The two parties announced the proposed merger this week. Chelsea is the UK's fifth biggest building society with more than £13m worth of assets, and has a 13-strong comms team with a heavy focus on CSR work.
'I think the Catholic team was impressed with our CSR credentials; we do a lot of work in the community,' said Chelsea divisional director, comms, Jeremy Hicks.
Industry insiders said the deal provides proof that proactive CSR can impact business deals - Catholic was courted by a number of interested parties.
Catholic had wanted to stay independent, but the 40-year-old mutual felt it needed back office support to grow. Part of that back office support is the comms team.Catholic currently has no internal comms support and the building society will now use Chelsea's press office.
Chelsea will also provide in-house PR support for the deal, but said it had a roster of agencies it could use for project work around the merger.
'This is day one, and we are reviewing as we go forward,' said Hicks. 'We've used two or three agencies in the past two years and are in contact with more.'
The merger, which will in effect be a takeover by the much larger Chelsea, is likely to result in a windfall for Catholic's 3,500-plus members. The deal has been announced but is not yet finalised, with discussions between the two societies continuing.
Building societies have featured heavily in the news since the credit crunch began last year and the Financial Services Authority has warned them to be vigilant.