John Kenneth Ambler (6 June 1924 – 31 May 2008) was a British businessman married to Princess Margaretha of Sweden.

Princess Margaretha and John Ambler were married in Gärdslösa Church, Öland, on 30 June 1964.

In the late 1950s he used Freddie Laker's Channel Air Bridge car ferry flights, from Southend to Rotterdam and Ostend.

Working with continental hauliers Ambler later established Trukair, a parcel delivery network connecting the UK and the Common Market and Scandinavia; this was a pioneering venture, before the inception of daily roll-on, roll-off ferry services between the UK and the Continent.

After business declined, the family had to vacate their home, Chippinghurst Manor (which was owned by James Gladstone McDougall, a member of a flour milling dynasty), and move to a smaller house.