Clifford, also chief executive at Nottingham-based broker If I Were You, starts four months after Mansfield’s chief executive Gev Lynott joined the mutual from Saga.
Lynott has plans to extend Mansfield’s intermediary lending and develop it as a specialist niche lender focused on buy-to-let, shared equity and ownership and equity release markets.
The mutual currently does more than 75% of its mortgage lending via brokers but wants to up the ante this year.
Clifford said: "I'm really pleased to be involved in the mutual sector again and joining the board of my home town's building society was the principle objective.
“The Mansfield is a trusted, safe and successful business and I'm looking forward to playing my part as a non-executive in its development over the next few years, particularly in the mortgage market."
Lynott added: “Rob is well connected in the industry and we are looking to do more with brokers this year especially in the buy-to-let, self-build and affordable housing sectors.”
Clifford is also a non-executive director with Scottish mortgage adviser MoneyQuest and sits on the board of Sesame Bankhall Valuations.
Lynott has worked in financial services at a range of firms including M&S Financial Services, Asda Financial Services and Abbey.
Mansfield offers mortgages up to 95% loan to value at a rate of 5.49% and free or subsidised legal fees and recently launched a range of buy-to-let deals starting from 3.75% up to 70% LTV with fees under £1,000.
