London’s auction week ran alongside Frieze London and Frieze Masters. It was clear that the auction houses would need one or two major single-owner sales to compete with two fairs of that scale. The big one was the collection of Peter Simon, founder of the Monsoon fashion label, at Christie’s. It ranged from recent work by Beatriz Milhazes to vast Bridget Riley paintings, and everything in between.

The collection was formed with the guidance of the London dealer Ivor Braka. I understand from a very good source that Simon gradually stopped involving his advisor towards the end of his collecting career. It shows. The early acquisitions are where the quality lies. The centrepiece was Francis Bacon’s Figure in Movement(1978), bought from Braka in 2006, which made £17.2m with fees. It hung alongside fine works by David Bomberg, Frank Auerbach and Leon Kossoff. The evening sale made £107.5m with fees, the highest total for a single-owner collection at Christie’s London, but some way off the £200m that the Lewis sale fetched at Sotheby’s in June. Other international artists made great prices too. Mondrian’s Composition A, with Double Line and Yellow(1935) realised £9.7m and was aptly for sale at the same time as the excellent Marlow Moss exhibition at Ward Moretti, well worth a visit if you have not yet seen it. A big surprise was the price of Lyubov Popova’s Painterly Architectonic (1918), which set an artist record at £7.6m and demonstrates the enormous gains made by female artists in recent years. Bona fide Popovas are as rare as hen’s teeth, and this work was easily comparable to Lissitzky or even Kazimir Malevich. Finally, the great David Bomberg’s San Miguel, Toledo, Afternoon (1929) set an artist record at £3.3m. The picture typifies the qualities that earned him the admiration of his more famous pupils, Auerbach and Kossoff. Bomberg is a real gem and his works on paper remain hugely underrated. Go and buy them before it is too late. Harsh it may be, but I feel there was too much flab in the day sales and towards the end of the evening sale. For every major Riley or Hirst there were five or six lesser pieces by young, hyper-contemporary artists. They belonged in a smaller saleroom or an online sale in New York in November. In these events the top lots always carry the weaker material at the back of the catalogue. However you look at it, the works bought with an advisor’s help were markedly better, and they made markedly higher prices.

The same evening, Christie’s 20th/21st Century sale was also star-filled and strong, led by Kandinsky’s Das bunte Leben (1907) at £31.6m from his Paris trip with Münter, though I find this price too dear for a picture that barely hints at the abstract works that changed art forever in the early 1910s. Mondrian’s Composition III(1920) followed at £25.2m on its auction debut. Though some found this painting a little lifeless, I find Mondrian’s 1920 series of grey-ground paintings among the most remarkable in art history. If one considers the reversion to the classical and the Rappel de l’ordre of Picasso and others in the early 1920s, this is as innovative as any movement that came before it. Worth noting from a market perspective is that the two evening sales together made £218.6m, more than double the total achieved on the same night last year.

Across Piccadilly, Sotheby’s had nothing like the same depth of quality. I liked several pieces in its Modern British sale, notably a gorgeous Lynn Chadwick, Little Girl II, which I underbid on for a client. But there was nothing of stratospheric value, and the sale made £8.5m in total. The Contemporary evening sale was stronger but made a relatively modest £45.9m with fees. It was led by a 1977 de Kooning abstract at £9.8m, a European auction record for the artist. Beyond that, it boasted a very beautiful large Richter, Abstraktes Bild (1992), at £6.7m, and a lovely group of Baselitz works on paper. It could not compete with Christie’s Mondrian, Kandinsky and the Simon collection. However, that was to be expected after Sotheby’s extraordinary sale of the Joe Lewis collection this summer. Sotheby’s neither wanted nor needed to take on the Christie’s juggernaut in October. Holding its major London sale in June rather than October was the right call. In October, two fairs in Regent’s Park hang a huge amount of competing material on their walls, and clients form their opinions against it. I always advise clients not to sell similar paintings in the same sale. You simply negate the advantage of being “one of a kind”.

I spent three days at Frieze Masters, and it was as beautiful a fair as I can remember. The standout stand was that of Hauser & Wirth. Alongside a beautiful small Freud, it showed Jan Brueghel the Elder’s Still Life of Flowers in a Stoneware Vase (c.1607-08). The Brueghel sold on the first day for around £5m, the highest price of Frieze week. The gallery also placed a Picabia for €1.1m and Picasso’s Violon (1943) for €850,000. Skarstedt, at the entrance, had installed a large Magritte and a very beautiful Twombly but, oddly, had a wall of Boudin crinoline scenes which were not entirely in keeping with the aesthetic, though they provided a welcome contrast to some of the more esoteric German post-war works elsewhere. I had many favourite stands, as always, but Offer Waterman, Ben Hunter, Patrick Bourne, Annely Juda and Richard Green all had superb presentations. Many combined strong Modern British works with old international superstars. Euan Uglow featured prominently around the fair. Patrick Bourne placed his Head of Christine with a museum. Uglow is a rare artist who deserves the international reputation that has, sadly, so far escaped him.

On the Monday I visited the Paris viewings at Sotheby’s, Christie’s, Tajan and Artcurial. My conclusion on the flight home was that Paris now stands on equal footing with London in the European art world. The quality on the walls at Christie’s and Sotheby’s equalled London’s October season, even with the Peter Simon sale. The Schlumberger collection at Sotheby’s, which totalled €74m, was the highlight. Its Monets were led by a late work, Iris, a painting never before exhibited and estimated at €22-30m. It was hammered down by Aurélie Vandevoorde at €43m, or €50m with fees, the highest price ever paid for a painting at auction in France. That seemed remarkable given that it was not, in my view, a great work. I was the underbidder on one of the smaller Monets and had no idea it would make nearly double its presumed value: €3.4m hammer against my bid of €1.5m. Christie’s same-day Paris sale, which boasted the collection of Durand-Ruel, made €41.6m. It included Monet’s Bord des falaises à Pourville at €12.7m and Trois pots de tulipes at €3.1m.

Much of the buoyant atmosphere came from Art Basel Paris at the Grand Palais. The riots of the previous weekend did not stop collectors arriving for the VIP days, despite anti-ram barriers and dog patrols around the building. Big sales came early. Hauser & Wirth, which also performed strongly at Frieze Masters, sold Richter’s Rococo Table (1965) for $10.5m. White Cube boasted strong sales, with two paintings by Julie Mehretu finding buyers at $7.85m each. I was also pleased to see that Ropac had sold a number of Baselitz works at prices of up to €800,000. The protests did catch up with the fair in the end, however, and it is closing early on Friday evening.

There is no question that the market is as strong as ever, and these two weeks of fairs, gallery shows and auctions make for wonderful viewing. But underbidders, and anyone kept from Paris by the riots or unable to get to London for Frieze week, should wait for the November sales in New York and the next round in Paris for a fuller picture. I cannot wait for the New York sales and the huge Blauquier-Arrieta collection to come to market. I shall be there to report back from 12th-18th November. Please, always use an advisor when buying expensive works of art. Do get in touch if you need help avoiding the pitfalls that sadly occur all too often when collecting works of art without expert guidance.