Inflation

Just seen fee ticket for Margowan Site for 15/9/1997. Pitch fee £1, Adult night £2-60 x 2, Elect £1-45-Total £7-65. The fees for the same night 2012 will be Pitch £6-35 (Now inc of elect) Adult night £6-25 x 2 Total £18-85. Allowing only for inflation what would todays site fee be?Even in the old days of candle power tills the club could segregate fees to Elect/Non Elect.Why not now? Anyone an expert on inflation figures to provide an answer please.