4G spectrum - why is 800MHz *so* valuable versus 2.6Ghz?

The UK 4G spectrum auction has just closed. I thought some of the prices paid looked a little fishy, so I put together a spreadsheet fit to the numbers, to try to work out what was paid for the 800MHz spectrum versus the 2600MHz spectrum.

We don't know how much was actually paid by EE or Vodafone for each of the two chunks of spectrum they bought: only totals were published. However, the auction process should mean that fairly similar amounts were paid per MHz for all the 800MHz chunks, and for all the 2600MHz chunks. You can use that idea to try varying how EE and Vodafone might have split their spend between the two bands, and solve in a spreadsheet to minimise the price differences across the board. I did this and ended up with an estimate of the price per MHz in the two bands, below (italics).

The surprise for me is: 800MHz spectrum is worth 6x as much as 2600MHz spectrum.

Sure, 800 penetrates into buildings better, but can that really be a fair price? Six times as valuable?

Mhz of spectrum Price paid per MHz Total Paid for Band
Winning bidder Total paid 800Mhz 2.6GHz 800MHz 2.6GHz 800MHz 2.6GHz
Everything Everywhere (EE) £589M 10 70 £27.5M £4.5M £275M £314M
Hutchison 3G (Three) £225M 10
Niche Spectrum Ventures (BT) £186M
Telefónica / O2 £550M 20
Vodafone £791M 20 65 £26.0M £4.1M £522M £269M
Total £2,341M