The Essential Information Group reports on a regular basis on the number of lots offered, and sold at auctions.
Their recent report can be seen here and says ‘for the past 4 months the overall monthly amount raised has seen a double digit increase when compared with the same month last year. In June of this year, it fell back 21%, from £392M to £309M.
The reason for this fall in revenue is principally because a major London commercial auction house held an auction in June last year raising £75M, but this year have held sales in both May and July but not June.’
More statistics can be seen in their newsletter.