Any chance of a photograph of the problem? Common problems with these shrubs are silverleaf, aphid and scale infestation, and sometimes fireblight, though the latter is more a problem in the south of the country.

Could it be coral spot - a fungus that spreads through dead and dying wood? If google images look like what you have, then your friend's hedge may need removing to a bonfire or the tip. If only a few branches are affected then you can try to cut these back to a green stem. On the whole, coral spot indicates a dead or dying shrub/tree etc. Best to get rid of and start again.