The price difference between the Double Six Apache Special (£1393.00) and the Club Series Double Six (£699.00) is £694.00 GBP pounds! In the catalogue Barry Gibson sent me it says that the Double Six Apache Special has "all the same features as the standard Double Six except fitted with the 12-string Rez-o-Tube tremolo system." So, it turns out that the 12-string Rez-o-Tube tremolo system alone costs £694.00 GBP pounds, the price of another Club Series Double Six!
I find this rather hard to believe, so I wrote to Barry and I look forward to his response . . .