I loved Sutcliff's children's novels set in Roman Britain (The Eagle of the Ninth is probably her best known), but I have never read her adult books.
From the blurb
Sir Thomas Fairfax, who was to become commander-in-chief of Cromwell's Army, is the stirring hero of this dramatic historical novel.
A frail man with a lion's heart and a puritan's conscience, his exploits on the battlefield became as legendary as the name by which he was known to the weavers and farmers who made up his army.
'Black Tom', riding his famous stallion White Surrey, became a symbol of hope for the northern towns of England.
With him in their midst men discovered courage which led them to accomplish such things as the raising of the siege of Leeds and the capture of Wakefield, described by historians of the time as 'more a miracle than a victory'.
And always behind him 'like any draggle-tailed camp follower' came his dauntless wife Anne, leaving the softness of her life as a gentle-woman to brave the bitter comforts of any army on the march because she believed her husband needed her.