The auction record for a painting by Sir Stanley Spencer was broken twice within minutes at Sotheby's in London.
Workmen in the House, which had an upper estimate of £2m, sold for £4.7m before Sunflower and Dog Worship, with a top estimate of £1.5m, fetched £5.4m.
The previous record was the £1.43m achieved at Sotheby's in December for 1954 work Hilda and I at Pond Street.
Lucian Freud's Boat on a Beach fetched £2.6m in Wednesday's sale - a record for a work on paper by the artist.
Sir Stanley, described by the auction house as one of the 20th Century's most important UK artists, was born in 1891 and lived and worked in the Berkshire village of Cookham, now home to a gallery of his work.
Seven of his works were sold in Wednesday's sale - the first section of a three-part auction of the Evill/Frost collection - for a total of £23m.
1935 painting Workmen in the House, which depicts the disruption and intrusion caused by tradesmen working in a kitchen, is one of Sir Stanley's best-known works.
Sunflower and Dog Worship, 1937, meanwhile, shows a husband and wife being embraced by giant flowers and explores Sir Stanley's notion of universal harmony.
Sotheby's senior director James Rawlin said a "series of new benchmarks" had been set for Sir Stanley's paintings "demonstrating both the strength of the market in this field and a particular appreciation for the artist's work".
Lucian Freud's 1945 work Boat on a Beach, which records a trip he made to the Scilly Isles, sold for £2.6m - way above the upper estimate of £600,000.
Earlier in the evening, his Boy on a Sofa, 1944, which depicts a young boy who tried to break into the artist's flat, sold for £1.5m.
Freud then persuaded the boy, Billy Lumley, to sit for a portrait.
An artist record for Edward Burra was also achieved with his Zoot Suits - showing a group of men who had just arrived in London from Jamaica in 1948 - selling for £2.1m.
Highs for artists including Graham Sutherland and William Roberts were also achieved.
Wednesday's sale fetched a total of £37.5m, compared with an estimate of £16m, with all lots finding a buyer.
The works being auctioned - described by Sotheby's as the greatest collection of 20th Century British art ever to come to the market - were collected by solicitor Wilfrid Evill between 1925 and 1960.
The collection was inherited and maintained by his ward, Honor Frost, an underwater archaeology pioneer who died last year aged 92.
The second and third parts of the sale take place on Thursday.
Artists up for auction include sculptor Henry Moore and LS Lowry.