Brit has become the latest insurer to join the influential group of top Lloyd's managing agents, known as the Group of Six (G6).
It replaces Wellington Underwriting as the sixth member of G6 after it merged with Catlin last month.
Brit will now begin work with fellow G6 members Hiscox, Catlin, Kiln, Amlin and Beazley to help modernise the market.
Brit Insurance chief operating officer Kathy Lisson said: "Brit Insurance has long been committed
to market reform and has taken a very active role in market leadership, systems development and performance improvement.
"Our joining G6 is a natural extension of these efforts and places us well to help ensure consistent standards are used across the market and that processes are re-designed effectively helping to streamline efficiencies."
Brit said its inclusion in G6 would complement the other initiatives that it is currently involved in, including the Market Reform Group, RI3K and electronic hubs and electronic claims initiatives.