Thanks so much...
you know when you've been staring at something for so long..
. Seems my errors were;
Calculating - used the performance limited landing mass in the calculations which meant I selected landing mass as the limiting figure, not the ZFM.
In the sheet - a simple transposition of 9870 versus 9780 in the PAX load was mucking the job up.
As an aside, I concur on the ramp limitation. Max Taxi Mass - 63,060kg which with a taxi AUW of 62,203, is 857KG