I thought the accelerator cable would go in without much resistance. In fact fitting it to the plenam bracket took less that 10 minutes. But - and there is a but. Once installed there is only about 1cm of travel which hardly opens the throttle. Mmmm. I thought about this for a while and tried repositioning the bracket, but in the end phoned GBS. It turns out that you have to cut 2cm off the plastic bracket and be very careful not to nick the cable itself whilst doing so. As you can see, once this is done you get full travel.
Finally I hadn't completed the lower end of the clutch cable assembly. I have seen various methods of securing the cable to the bell housing, but I haven't any nylocs with the correct thread so it will simply have to remain with the 2 lock nuts for now.
Here is a view of the pedal box with everything now in. I did decide to re-seat the accelerator pedal as I wasn't happy with the fact that it didn't swing freely. The pre-drilled hole in the pedal box needed widening slightly and with a little grease applied it felt a lot better.