No idea, sounds like it had been trained - there are two plants commonly known as Laurel - Aucuba japonica and Prunus laurocerasus - the Prunus is more likely to take to that kind of training.

I wonder if its a Camellia you saw?

I went to the Clarence House garden parties and took some photos. There are evergreen bushes trained right up against the wall in a couple of the photos which I'll upload.

http://www.growsonyou.com/photo/slideshow/182667-potting-shed-ideas/member/beattie

Sorry the bushes in question are right on the edges of the photos, but someone may be able to id them. They look like laurel to me.

Magnolia grandiflora. :-)

Wow thyanks Fractal! I didn't know it could be trained against a wall. :-)

Yes, this evergreen species has and is often trained against walls. I have a picture of one I took myself against a wall which I will try and find and post.

Just uploaded a picture of one I took at Cliveden House last year.

http://www.growsonyou.com/photo/slideshow/182800-magnolia-grandiflora/member/fractal

Gorgeous, Fractal. Thanks :-)