In buying LMG, will gain the UK's largest loyalty programme company, , along with the shopping details of around 10m people already signed up to the plan in the country. Nectar has loyalty agreements with a host of major UK brands including Sainsbury's, BP and Debenhams.
Aeroplan, a loyalty marketing company that provides the air miles programme for Air Canada, among others, acquired Nectar from owners Sir Keith and the private equity company Warburg Pincus.
Sir Keith will gain around £160m while Warburg Pincus will earn a return of more than six times its original investment in the business.
It is understood that the existing management team at LMG, which includes its co-founder and chief financial officer Alex Moorhead, will stay on as part of the acquisition, which has been approved by LMG's shareholders.Nectar was formed by Sir Keith and Moorhead in 2002 with the aid of £25m worth of Warburg Pincus funding. Mills embarked on the venture after selling AirMiles, the scheme he devised, to British Airways.
Nectar has become the UK's most popular loyalty scheme programme, and marked its fifth birthday in October with a major digital rebranding exercise featuring the tagline, "You deserve it".
Sir Keith said: "The company has grown rapidly in recent years and the Nectar programme has become the largest customer reward programme in the UK.
"All shareholders strongly believe Aeroplan is the right partner to take the business forward and successfully realise its next stage of growth."