Barbara Hepworth's Sculpture with Colour (Eos) changed hands in London on Wednesday for £6.19 million, a new auction record for a one-of-a-kind work by the British modernist. Christie's had valued the 1946 carving at £5 million to £8 million, and the result landed comfortably inside that range. The house said the figure marked the highest price ever paid for a unique Hepworth.

The sculpture arrived with heavyweight credentials. Cut and painted in the artist's St Ives studio shortly after the Second World War, it is one of only three known stone pieces from 1946 to carry applied colour. Pale Hopton Wood stone gives the ovoid form its bulk; three scooped hollows picked out in blue, grey and white give it light. It starred in the Courtauld Gallery's Hepworth in Colour exhibition earlier this year, and in 1946 Lee Miller photographed the artist beside the work for Vogue.

Wednesday's sale was effectively a Hepworth benefit evening. Her works took the three highest prices of the night: behind Eos came the elm Figure (Sunion) of 1960 and the bronze Sea Form (Porthmeor) of 1958, one of seven casts and the last still in private hands. Elsewhere in the room, Euan Uglow's 1993 Pyramid set a fresh artist record at $1.06 million, and Walter Sickert's The Horses of St Mark's, Venice did the same at $734,600.

The evening totalled $30.8 million (£23.09 million), in line with the pre-sale estimate. Not everything found a buyer: five lots, including a 1947 Henry Moore, were bought in, and three more were withdrawn before the sale opened.