hep in tree identification
 

Hi
I have just come back from a visit to my parents in law in hertfordshire. They have a lovely tree in the back garden. It is about 6 foot tall and on a stem about 4 foot tall. The foliage is a spherical shape with light green/silvery leaves. It has pink leaves on it at the moment. My mother in law thinks its name begins with a k. I would love to buy one but am a complete gardening beginner. Any ideas as to what this might be please?