Thanks guys, very interesting useful responses, just what I was after.
As a couple of you asked, I did quote the chap correctly, and his statements are in supporting documentation for a mature beech that was felled very locally to the trees I am applying for. It was the local Residents Association who quoted him in their letter to my customer. I thought that it sounded quite an extreme quote, so I double checked myself that they had quoted him correctly!
I liked AA Teccie Pauls remark that I should state something similar to "...to a height/clearance above ground level not exceeding '5.0m' and by removal of secondary and tertiary (third order) branches only, no primary branches, and with final pruning cuts not exceeding 75mm dia." (or similar). If the application is refused I'll try and improve my wording a little!
On another slightly separate tangent, a couple of years ago I had a job where I applied to cut back some overhanging branches from scrappy boundary trees (sycamore, ash, and a many years previously butchered oak). The limbs were almost entirely across the customers gardens, (a row of terraced houses) almost touching the roof in a couple of places. My application came back with the conditions of cutting back by a maximum of 1.5m. There was no access for cherry pickers, and on some of the trees, there would have been no way for me to climb out far enough to cut back such a small amount.
The odd thing was that all 5 of the residents in the terraced row of houses disliked the trees, they weren't visible from the road or anywhere except the 5 resident's homes. So I didn't understand how they could have provided any amenity value.
I didn't fancy arguing the toss with the council and rocking the boat, so I told the customer to track down a consultant. Not sure what's happened since, they aren't the easiest trees for me to easily go and have a look at.
All the fun of the fair