248th (Welwyn) Heavy Anti-Aircraft Battery, Royal Artillery, was an air defence unit of Britain's Territorial Army (TA). Formed just before the Second World War, it fought in the Battle of France and the Swansea Blitz, and later defended London and Cyprus. It continued serving in the post-war TA until 1955.

3rd Anti-Aircraft Brigade was a Supplementary Reserve air defence formation of the British Army formed in Northern Ireland in 1938. On the outbreak of the Second World War it saw active service with the British Expeditionary Force during the Battle of France and Operation Aerial. It then returned to Northern Ireland and defended the Province for the next two years. Postwar, it was reformed in the Territorial Army and served until the disbandment of Anti-Aircraft Command in 1955.