Thanks for the replies. The 148 is a fan belt not PAS which is wider. Looking at various ebay and other suppliers there are a few who could do with the loan of Johns glasses. Some list belts as P5b power steering belts that have as much chance of fitting as I have of being Naomi Cambells toy boy.
The part number for the original PAS belt was ERC 1347 according to a couple of sites the equivalent still has modern applications (Alfa Romeo) being one. I've found a belt that I've cut and joined to fit with the adjuster 1/2 way and taken it apart again to get the measurements,Goodyear and Gates list a belt that should fit.I'll order one and if it does post the numbers on here.