Put on public display nearby Christie's King Street saleroom in St James's Square, Jeff Koons' Balloon Flower (Magenta) sold at a record £11.5m at their evening sale on June 30.

Enjoy unlimited access: just £1 for 12 weeks

Subscribe now

A remarkable £224m hammer total was set by the three main salerooms - up from the £217.7m seen for the February series in London and the £193m seen in the equivalent sales last year.

However, the meteoric growth rate appears to have slowed - the £224m total is only a 16 per cent year-on-year rise compared to the 300 per cent increase seen between the summer sales of 2006 and 2007.

Sotheby's held the most lucrative sale of the series - their 75-lot evening sale on July 1 which made £82.4m against a pre-sale estimate of £67.4m-96.6m.

All bar four lots found buyers, with the highest price being Study for Head of George Dyer by Francis Bacon (1909-1992), which saw interest from at least four bidders before it was knocked down to a telephone buyer at £12.25m.

With a low estimate of £8m, it was one of 25 guaranteed lots at the sale.

The psychologically arresting 14 x 12in (36 x 30cm) portrait of the artist's lover has been requested for the forthcoming Bacon exhibition at the Tate which opens in September and will travel to the Prado in Madrid and the Met in New York next year. Regarded as an important work in the artist's canon, the vendor bought it from the Marlborough Gallery two months after Bacon painted it in 1967.

But the other Bacon on offer, the privately consigned Figure Turning, came with a punchy £10m-15m estimate and was unsold after failing to attract a single bid.

This 6ft 6in x 4ft 8in (1.97 x 1.41m) work from 1962 demonstrated that despite the phenomenal rise in the artist's value, the ten or so big Bacon buyers who operate at this level remain selective.

Among the 11 artist's records at the sale was Antony Gormley's (b.1950) Angel of the North (Life-size Maquette) from 1997 which made £2m against a £600,000-800,000 estimate.

Standing 6ft 7in (2m) high, it was one of five cast-iron prototypes produced in preparation for the iconic sculpture in Ke auctioneers had given a guarantee of around £10m.

In all, Christie's guaranteed 14 lots. The sale set nine artist records including Jeff Koons' (b.1955) Balloon Flower (Magenta) that sold at £11.5m. With a transparent colour coating and mirrored surface, the 11ft 2in (3.4m) high stainless steel sculpture was one of five versions of twisted balloons produced by the American artist between 1995 and 2000.

This one was being sold by the Dallas collectors Howard and Cindy Rachofsky who had bought it seven years ago for around £600,000. Heavily guaranteed, it was thought that offering it in London would help attract Russian and Middle Eastern interest. The auctioneers put it on public display in St James's Square.

The previous record for Koons was $21m (£10.5m) for Hanging Heart (Magenta/Gold) sold at Sotheby's New York last November.

Another record, and perhaps the most hotly contested lot of the series, was arguably the first major work by Gilbert & George (b.1943 & 1942) to be offered at auction. Entitled To Her Majesty, the gelatin silver print in 37 parts brought interest in the room from Europe and America as well as at least three interested parties on the telephone. It soared beyond its £400,000-600,000 estimate, selling at £1.55m, over three times the previous record.

Phillips de Pury's evening sale on June 29 met with a more tepid response with 31 of the 91 lots unsold. The hammer total was £20.9m, which was £8m below the pre-sale low estimate - a reflection of the less-than-stellar content.

The top lot did, however, generate good competition. A late Willem De Kooning (1904-1997), Untitled from 1984, was bought above estimate by London dealer Ivor Braka at £3.1m.

By Alex Capon