Led Zeppelin's one-off O2 Arena gig last December commanded the highest price on the U.K. secondary ticket market in 2007, while Take That's tour generated the most sales according to new figures from independent ticketing research consultancy Tixdaq.

London-based Tixdaq found that Take That generated a total of £12.8 million ($25.7 million) in sales of secondary tickets on internet exchanges last year. The pop act were followed by Scotland's T In The Park festival, which generated £8.7 million ($17.4 million) in secondary sales, and the two-site V Festival in Chelmsford and Stafford with £6.7 million ($13.4 million).

The Spice Girls were the next biggest act on the secondary market with sales of £5.3 million ($10.6 million), followed by the Reading Festival with £4.9 million ($9.8 million), Prince with £4.2 million ($8.4 million), The Police with £3.4 million ($6.8 million), George Michael with £3 million ($6 million), Genesis with £2.9 million ($5.8 million) and Bruce Springsteen with £2.1 million ($4.2 million).

The average ticket price for Led Zeppelin's Dec. 10 reunion show at London's O2 Arena was £707.97 ($1,421.79), despite security measures designed to prevent tickets to the benefit show being sold on. The next highest average was for Sir Paul McCartney's Oct. 25 "Electric Proms" show at London's Roundhouse, with prices reaching £498.14 ($1,000.39).

"These figures give a fascinating insight into the scale of the secondary ticketing market in the U.K.," said Tixdaq founder Will Muirhead in a statement. "Secondary ticket exchanges -- like Seatwave, Viagogo and GetMeIn -- have created a £200 million [$401 million] market in concert tickets in the U.K. in just a couple of years, and valuations for the leading firms are now well in excess of £50 million [$100 million] each. No wonder artists are concerned that they do not generally share in the proceeds."

Muirhead claims that his company is meeting a recent Parliamentary committee's call for more research into the new market for second-hand tickets, and says more transparency is required to ensure consumers have complete trust in the tickets advertised online.

Tixdaq monitors secondary sales on the 25 most popular sites in the U.K. and has plans to extend its monitoring services to Europe and the United States.