Adaptor converting frame from Rim to Disc brake

[Pat "5mph"]

Thanks for the replies, guys.
We have fitted a bigger disk with no joy, we have not tried flipping the adapter.
Will tell @KatyO who is the lbs mechanic.
She is teaching me lots of useful stuff

 

[Pat "5mph"]

Edit @I like Skol: looking again at your picture, we did try fitting it the other way, still the disk would not reach.
The largest we had available in the shop to try was 180 @Yellow Saddle

 

[I like Skol]

The largest we had available in the shop to try was 180

You wouldn't want anything bigger than 180 on the back anyway, it would be over braked with a 180mm disc.