Sir Alan Abraham Mocatta, OBE (27 June 1907 – 1 November 1990) was a British judge, an expert on restrictive practices and a leader of the Spanish and Portuguese Jews of Britain.
In World War II he first served as 2nd Lieutenant in 12 LAA Regiment, RA, TA, 1939, and was promoted to brigade major, 56 AA Brigade, 1940–41; to GSO (2) AA HQ BTNI, 1941–42; and finally to Lieutenant-Colonel General Staff, Army Council Secretariat, War Office, 1942-45.
Returning to his legal career after the end of the war, he was appointed QC in 1951.
He served as a Judge of the High Court of Justice (Queen's Bench Division) from 1961 (the year in which he received his knighthood) to 1981.
At the 1962 Winter Assizes in Carmarthen, he presided over what was then the longest criminal trial in British legal history, sitting for 55 court days in what became known as 'The West Wales (or Black Mountains) Lime Fraud enquiry'.