The cost of the upgrade is neither here nor there, though £109m is far short of what will actually be required.
The important savings to be gained are from the running and support costs for the time during which the aircraft would have continued in service, and the savings from ending logs support for an entire aircraft type.
Besides which the Thai Navy need 'em!
And why do we need an Empire-driven Blue Water Fleet anyway?
I'm battening down my hatches and putting a funny white hood on right now.....