Dirty Sanchez,
There's a LOT you don't understand..........................
Cancelling Tranche 3 will not save a penny thanks to extremely stringent contract penalty clauses introduced by the UK some years ago to ensure that Germany did not cut it's commitment. It would also result in a painful renegotiation of national workshare.
Replacing the Jag and F3 fleet is hardly relevant to todays front line. The existing 2 frontline squadrons will probably only be increased by another three to give 5 squadrons as the original "Jag/F3 replacement" whereas Tranche 3 and the rest will be useful to replace part of the GR4 force along with the JSF as there is a stated intent to only have a FJ front line composed of these 2 types.