I had one similar to what you described here. I cut it down as it was not growing straight, it looked wrong, I cut it to about 14inches, it is already shooting new shoots all over the place. But... that was me, I do not know about anyone else who may have done so....how successful they were.

Cut it down, by two thirds. Be brave. Worthy

I agree be brave cut it down as described by worthy.

Right! Thanks very much! I'm plucking up courage and hope to perform the operation in the morning!

Practically all Eucs stump sprout enthusiastically--that's how they survive brush fires in Australia.

I would wait a month or two before carrying out the cut. I think you might find the tree sprouting early new growth in a mild spell which then gets frosted and killed spoiling your tree this year.

Cut it down in March, unless we still have arctic conditions - you can cut it down to 6 inches if you're feeling really brave (I know, because I've done it loads of times) - it will respond by producing lots of new stems from the ground. Do this every year, and you'll have a bluey grey shrub about 8 feet high by the end of the growing season each year with juvenile leaves only. It does mean, though, that there'll be a bare spot in the border after stooling each spring, but it grows, as you know, very rapidly.
If you want more of a tree than bush, let the main stem get to, say, 3 or 4 feet, then keep the top trimmed throughout the growing season to a sort of lollipop shape, or a teardrop, whatever you fancy - this is more work and requires constant attention though because Eucalypts have strong 'apical domination' which means they always produce a shoot that reaches for the sky as quickly as possible - cut that one, and another one or 3 take over.

Thank you all once again. Luckily I had a look on here this morning before reaching for the saw, so I'll wait until March! I love the idea of an annual 8ft shrub with only juvenile leaves.