The two brands have joined Tesla as confirmed attendees, while the show's organisers are believed to be still attempting to sign up other manufacturers.
MG is the first manufacturer to sign up, and will be displaying its two main models, the MG 3 and the MG 6, at the show. While the manufacturer says that it has “several models planned for the immediate and longer-term future”, it has not confirmed whether any of these will be appearing at the show in the form of concepts or production models.
Mazda, however, will be represented at the show by dealer group T W White & Sons. The group, based in the south of England, will be displaying a selection of Mazda’s new range, with the 2, 3 and MX-5 all expected to be on show.
The dealer group has also confirmed that the MX-5-based Mitsuoka Roadster will also be on display at the show.
At a previous press event for the show, HRH Prince Michael of Kent announced that Aston Martin, Jaguar, Land Rover and Geely had agreed "multi-million pound" investments to exhibit at the revived London motor show in May 2016.
However, a spokesman subsequently clarified the comment, making it clear that the Prince actually meant to acknowledge these three firm's investment in the UK car industry.
The show will run from 5-8 May 2016 with adult tickets priced at £13. No prices for concessions were revealed, but they were said to be "substantially lower". Prince Michael said the goal is to make the show "rank alongside cities like Geneva and Frankfurt".
He added: "The show will be an opportunity to shine the spotlight on one of the most amazing industries that we have in this country. The show is a very important development for the British motor industry and has come about of its remarkable success."
Although no specifics were given, the show will be built around "several large structures" which will act as hubs to put a focus on various aspects of the motoring industry, including its heritage in an area led by the Beaulieu National Motor Museum, a zone where thought leaders from the industry will be available for seminars, an area focused on road safety and a test drive zone. In addition, Prince Michael revealed that a heliport will be running to take potential customers to race tracks for high-speed test drives, and that there would be an emphasis on family entertainment.