Don't forget Typhoon
I support Lewis but a key point he is missing is that in assessing what aircraft are needed it's not just a Harrier vs Tornado debate but it's about the whole RAF inventory.
All of the weapons carried by Tornado can be carried by later batches of the Typhoon. There are therefore no capabilities that we would be loosing from the RAF inventory if we withdrew Tornado. You would still have a twin engined, high speed combat airctaft capable of carrying LGB's, Storm Shadow, ALARM, etc.
You do have capabilities in the Harrier that are not available elswhere in the inventory, most particularly the ability to operate from a carrier.
We are therefore losing more capability by withdrawing the Harrier (whose capabilities are not reflected alswehere in our aircraft inventory) than the Tornado (whose capabilities are available elsewhere in the inventory).
A sensible review would have:
1) Scrapped Tornado and used some of the savings to fund more Chinooks, C117's and air to ground capability for the Typhoon and Nimrod
2) Kept the Harrier
3) Kept Nimrod (after we've paid all the money for it) but given it an LGB capability so that it could be used in a loitering bomber role in the way in which the US use their B52's and B1's thus giving it more relevance than a purely ASW platform.
4) Kept Sentinel given its relevance to COIN operations.
5) Transferred all RAF helicopters to the Army Air Corp and saved all the staff office jobs created by the joint helicopter command.
Sadly we just got stupid Treasury inspired salami slicing removing a little bit of every type of capability as per every set of defence cuts dressed up as a defience review over the last 20 years.