EHS saw off competition from TBWA/GGT to retain the account.
Its brief will be to build awareness of the Government's new savings products. The first campaign to emerge in the wake of the appointment will stress the stability of government investment, selling it as a safe alternative to the fluctuating stock market.
NS&I has relied heavily on direct marketing over the past two years.
EHS Brann has been the organisation's lead creative agency since BMP DDB's above-the-line contract expired 18-months ago. During this time, EHS has handled all of NS&I's brand advertising.
Last month, NS&I signalled its intention to refocus its energies on above the line by hiring Walsh Trott Chick Smith. This followed a three-way pitch that also involved Publicis and St Luke's.
OMD UK was retained as its media and planning agency, with Ptarmigan Media handling specialist, trade and financial press advertising.
NS&I rebranded through Citigate Lloyd Northover in February this year.
The rebranding process cost around £2 million and was followed by a press and direct marketing campaign for premium bonds that featured the strapline: "National Savings & Investments can make you a millionaire."
NS&I products are differentiated from other financial service offerings because consumers are guaranteed that they will be returned at least their original investment, regardless of the performance of the stock market.
The Government is able to make this guarantee to investors because HM's Treasury protects all money entrusted to NS&I.