By Holly Williams, PA Business Editor & Lawrence Matheson The Nisbet family is set to bag a fortune after striking a £339 million deal to sell catering equipment company Nisbets to distribution giants Bunzl. Bunzl will get an 80 per cent slice of the firm, valuing Nisbets at over £500 million. Founder Andrew Nisbet will step down to become a non-executive director. Key West Holdings holds the Nisbet family’s business interests. Some 1,800 workers will be kept on and Bunzl also has the choice to buy the final 20 per cent of Nisbets in the future. Bunzl chief executive Frank van Zanten said: “An…