Reducing in height a leylandii hedge in winter

[akearn]

I have a leylandii hedge that is at present 12 metres long 2 metres high and 1 metre wide it was reduced to its present size about 15 years ago when it was about 7 metres high.
Would it be safe to shortening the height by about 1/2 metre at this time of the year.
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Yes. It will be fine but feed it blood fish and bone in the Spring and again in the Autumn.