is it a private message?
Lizzie-nothing has appeared
Have you cut them back at all in those 4 years?
How tall are they now?
How tall do you want the hedge to be?
depending on the size of cutting it might take awhile,I grew one from a cutting from cam hill and still have it twenty years on,took time.
Odd-try giving it a good high nitrogen feed soon -growmore will do- or something similar- to give it a boost
I planted a whole row of these last winter, they have done nothing, if they don't pick up this year I am having them out and replacing with laurel, which I also planted a row at the same time and they have come on beautifully. Nothing to look at but makes a lovely hedge.