He takes the seat of Jeff Hewitt, who has opted to stand down.
Mr Wilton qualified as an accountant with PricewaterhouseCoopers and spent 120 years with the merchant bank Rothschilds. He was finance director of WYG for three years until December 2011, since when he has been a self-employed financial gun-for-hire.
Sweett chairman Michael Henderson said: "David's background and business expertise will be invaluable to Sweett Group's board as we continue to develop our business strategy and grow our brand."
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