BR3 Part 6 says:
3917. Submariner Badge
The Submariner Badge consists of the QEII commissioning crown sited above two heraldic dolphins. The badge is of gilt and can be worn by all RN qualified submariner personnel as follows:
a. Blue uniforms. On the left breast of the reefer jacket between the lapel and the shoulder, horizontal, level with the point of the lapel. The badge should sit 6mm above medal ribbons or medals. On the mess jacket, a miniature badge is worn on the left lapel, 25mm below the point of the lapel, 6mm above miniature medals.
b. White tunics, bush jackets and khaki/stone coloured uniform. In accordance with Para 3915 c sub para 2:
"White tunics, bush jackets and khaki/stone coloured uniform. Fixed with ‘pin and clutch’ attachment 38mm centrally above the left breast pocket. If medals or medal ribbons are worn, the badge is to be worn centrally above the medals or top row of ribbons. On the white mess jacket, miniature badges are worn centrally on the left lapel over miniature medals".
c. No 3A uniform. A miniature badge, as worn on Mess Jackets, may be worn, horizontally, in a central position on the tie. The miniature badge is paid for at own expense.
d. No 3B uniform. Fixed with a 'pin and clutch' attachment, horizontally, 38mm centrally above the left breast pocket.