ORAC - major brain fade on my part - I thought "Previously, the UK government had said that no decision would be made until it understood the time and cost implications of the upgrade." meant the statement you highlight and didn't register the year.
However, given the timescale of the UK purchase not upgrading the majority makes little sense IMHO. The cost of the upgrade would surely be partly offset by savings in the cost of maintaining incompatible sub-systems?