The publisher apologises that upon publication an error was made in the equation listed for (4.3c) with + having been replaced in error with an x.
The correct equation is below:
Additionally a semi-colon was listed with in the second point within the conclusions section that was not required. The correct text is as below
(ii) optimally truncating the divergent expansion at $N \sim 1/B$ and considering the exponentially small remainder $\bar {q}$ by a solution of the form $q=q_0+Bq_1+ \cdots$ $+ B^N q_N + \bar {q}$;