Yew is the bestest hedge, but it'll take five years to blot out your oil
tank.
It is however smart, evergreen and will take any amount of clipping and
regrow from old wood.

It may well have to be Yew, perhaps I'll be able to get some larger than
usual one's. What about the root system, could it interfere with the plinth
under the tank??

Sounds like you're out in the country though, so
you may want a more informal hedge. A bit faster, informal, but deciduous
is Quickthorn, which I hear is faster to develop than Hawthorn.

I love Hawthorn but we are absolutely surrounded by it here, I was hoping
for something a little different from the norm.

For rapid results this summer, how about Leycesteria Formosa,
the Pheasant Berry, decorative, flowering bracts and berries, slightly
exotic, and will get to six feet in one season? It dies down to nothing in
the winter though!

That sounded hopeful till the dying down part

Not sure about its reaction to howling wind. Just some
thoughts,

Much appreciated Andy

Shan