I really can't disagree that the United Kingdom should have a dedicated RAF aircraft for Royal and State / Ministers use - but only if we are an independent nation, outside the EU. As an EU member, we have no need of such a frippery; our Prime Minister is no more important than the Chairman of the local Parish Council, we have no seat at the WTO, no place at the UN and we are headed by an unknown and unelected foreign bureaucrat.
So yes to Cameron's proposed conversion of one of the RAF's A330 tankers (which can also seat 291 PAX) but only if the 'Leave' campaign succeeds. If we stay in, we don't need it.
The arguments are becoming very clear that if we leave the EU we gain unarguably in status and global influence and the EU without us is diminished as a world player. Our WTO seat and our place on the UN Security Council, together with our nuclear capability and our place as the world's 5th largest economy, and as leading Commonwealth nation, mean we deserve a State aircraft.
Now let's please just make sure it's repainted in that lovely dark Royal maroon ...