Gentlemen!
In late 60th RAF tested twin MG gun pod for Wessex helicopter. How this pod could be attached to helicopter?

Probably over the wheel, see http://stingraysrotorforum.activeboard.com/t47293461/westland-whirlwindwessex-gun-armament/

lots of nice wessex piccies here BTW

http://www.pprune.org/rotorheads/123915-what-about-wessex-makes-people-so-fond.html