Sir Nicholas has applied to the Northern Ireland Court of Appeal for leave to have Susan Christie's jail sentence reviewed, his London office confirmed last night.
Christie, 23, a former member of the Ulster Defence Regiment, was jailed for the manslaughter of Penny McAllister, after a jury at Downpatrick Crown Court last month cleared her of murder.
But the sentence outraged Mrs McAllister's parents and her husband, Captain Duncan McAllister, 31, Christie's former lover, who felt it was too lenient.
With 50 per cent remission for good behaviour, Christie, from Lisburn, Co Antrim, could be released from Magheraberry prison in just over a year. Sir Nicholas took the decision after considering transcripts of the trial, the address to the jury by the trial judge, Lord Justice Kelly, and his comments as he passed sentence.
Christie claimed she could not remember attacking Mrs McAllister with a butcher's knife as they walked together at Drumkeeragh Forest, near Ballynahinch, Co Down, in March last year.