British physicist and Nobel prize winner.

Blackett won a place at Osborne Naval College in 1910. His training was interrupted by the First World War when, although only 16, he was made midshipman of HMS Carnarvon. Later he moved to HMS Barnham, on which he witnessed the battle of Jutland and devised an improvement in gunnery.

After the war Blackett was transferred to Cambridge where he became caught up in physics and resigned from the Navy. He graduated in 1921, subsequently becoming a fellow of Magdalene College.

His early research was under Rutherford at the Cavendish Laboratory, where his first task was to investigate the a-particle bombardment of nitrogen using the Wilson cloud chamber. By 1924, having taken over 25,000 photographs, he had evidence for the disintegration of the nitrogen nucleus predicted by Rutherford.

In 1932 Blackett began to research cosmic rays with Giuseppe Occhialini, again using the cloud chamber to record the paths of incoming particles. To improve the efficiency of the procedure they linked the chamber to Geiger counters, which triggered it on the arrival of a charged particle. With their improved apparatus they soon discovered positron tracks (although not before Carl Anderson in the United States) and showed that positrons and electrons were usually produced in pairs.

In 1935, while working at Birkbeck College, Blackett was appointed to the committee on air defence chaired by Henry Tizard which recommended radar development. Throughout the war and afterwards he was a key scientific adviser to the government. He was also instrumental in Indian scientific development - his advice was first sought by Nehru in 1947.

In 1948 Blackett received a Nobel Prize 'for his development of the Wilson cloud-chamber method and his discoveries therewith'. In 1965 he was appointed President of the Royal Society, gaining his peerage four years later.