Brown is chief executive of Braveheart and an executive director at RMS, which has stakes in engineering group Gyrometric and security consultancy Cloudveil.
The cost of the deal is £329,000 at 0.275p per share, the closing mid-price on 29 June, with the consideration to be paid through the issue to Brown of 2.63mln shares at a price of 12.5p.
Upon completion, Trevor Brown will no longer have a holding of ordinary shares in RMS, which posted losses of £712,000 in 2019.
Braveheart also has a 19.5% interest in Gyrometric and said it is intended that Trevor Brown will remain on the RMS Board to represent its interests.
Following completion, Brown will have a 24.75% stake in Braveheart.
Braveheart added that its independent directors, Jonathan Freeman and Vivian Hallam, and Allenby Capital, its nomad, said they considered the terms of the deal were fair and reasonable.