First, I would take off all of the older fronds, just leaving those that grew last year. Usually there is a narrow bare ring on the trunk between each year's fronds. If that isn't sufficient, and it has multiple trunks, saw off the trunk(s) that cause the most obstruction. If it's a single trunk, you may have to transplant it.

Thank you for your advice. As the palm is in a client's graden I will have to get her clearance for such a drastic haircut! The palm is about 5ft high and 6ft across! It is such a beautiful specimaen and they are so expensive to replace I am terrified of Killing it!!

Sounds like a single-trunked one, Maggi. Fortunately, they are fairly easy to transplant in the spring. About 2-4 weeks before the new leaves would normally come out--late March to early April here, I don't know about on Skiathos--I would cut off about half the leaves, and immediately dig it up, with a generous rootball. Don't plant it any deeper than it was originally,water it in well, and use some seaweed extract as a root stimulator. Hope this helps!