Anti-aircraft guns. Although the kit plans ignore them and no parts are included, all the round table class trawlers carried AA guns on the wings of the bridge, but there seems to have been no consistency as to the type and I guess it was more what was available at the time. From some photographs Sir Kay, (at least in April 1943), carried twin 303 Hefahs. I confess I had never heard of a Hafah and a quick bit of research showed they had a very short shelf life. Adopted formally in 1942 by the Royal Navy by 1944 the gun was declared obsolete, can't find a reason.
Others where fitted with Brownings, Vickers or Lewis among others and later single 20mm Oerlikons. As I am hoping to show Sir Kay as she may have looked around D day I have swapped the Hafah 303 for 303 Lewis, conveniently producer by Eduard 3D printed and intended for the Anson Mk 1 aircraft. From photographs the twin guns where mounted behind an armoured shield, these I built from 0.25mm styrene sheet. the shields where painted RN white and weathered. Looking at the finished pic. I think 'over-weathered' a better description so I may redo them, but anyway this how they look so far.