My understanding is that this particularly nasty incident happened on HMR 117 (the most Southerly Aberdeen radial) at about 130nm. As a matter of fact (from the F3 pilot's report) he was flying at 300kts at the time of the airprox. Some good comments here, not least the fact that the HMR structure covers a very extensive piece of sky. If it was made Class F, this would pose the following problems:
a. Who would provide the mandated ATC service? There is no point in providing CAS if you cannot control within it! The rig operators would have to stump-up a significant amount of money; how willing are they to do this? Right now, even the RT infrastructure isn't that brilliant!
b. Under the current regs for Class F, only participating ac would be involved. Consequently, without the introduction of additional systems such as radar, ADS-B, ACAS etc, the only risk reduction would be between helos flying the routes.
Finally, and somewhat emotively, why do these arguments always come down against "cowboy and uncaring" FJ operators. It seems to me that they are equally keen to avoid bumping into other aircraft. The title of this thread could have easily been:
"Bristows Puma has near miss on Tornado 130nm from Aberdeen"