Task: Question Answering
Input (English): Passage: Though generally a commentator rather than a campaigner, Lancaster made an exception for the protection of Britain's architectural heritage, where he became a leader of public opinion. The historian Jerry White has written that the demolition of the Euston Arch in London in 1962 alerted the general public that "without vigilance and sturdy resistance, London was in danger of losing its landmarks one by one, in the interests of either profit or a misconceived public weal". Lancaster had been pressing this point since before the war. In 1967 he was appointed to the Greater London Council's Historic Buildings advisory committee, joining Betjeman, Pevsner and Sir John Summerson. They played a major role in defeating the Labour government's plans to demolish the front of the Tate Gallery. In 1973, with Betjeman and others of like mind Lancaster campaigned against the Conservative government's imposition of entry charges to hitherto free galleries and museums; the charges caused admissions to drop drastically, and were soon abolished.In June 1975 Lancaster was knighted in the Queen's Birthday Honours. He and his wife collaborated on The Pleasure Garden (1977), a history of the British garden. Although great gardens such as Stowe were given full coverage, her text and his drawings did not neglect more modest efforts: "The suburban garden is the most important garden of the 20th century and there is no excuse other than ignorance for using the word 'suburban' in a derogatory sense". The following year Lancaster was made a Royal Designer for Industry (RDI) by the Royal Society of Arts, a distinction in which his predecessors had included the artist and architect Hugh Casson; the typographer Eric Gill; Charles Holden, London Transport's architect; Barnes Wallis, the wartime engineer; and a modernist architect with whom Lancaster had vigorously crossed swords, Sir Basil Spence. There would not be another theatre designer RDI until Stefanos Lazaridis in 2003. In 1978 Lancaster suffered the first of a series of strokes, and his health began a slow decline. He designed no more for the theatre, drew his last pocket cartoon for the Express in May 1981, and published his last collection, The Life and Times of Maudie Littlehampton the following year.Lancaster died at his Chelsea flat on 27 July 1986, aged 77. He was buried with previous generations of his family in the churchyard at East Winch. A memorial service was held at St Paul's, Covent Garden in October 1986. 
Question: Who played a major role in defeating the Labour government's plans to demolish the front of the Tate Gallery?
Output (English): Betjeman, Pevsner and Sir John Summerson.