Sophie and Beth had to cope with the loss of their sons, while under the care of UH Sussex NHS Trust.
Sir Keir Starmer says comments by the businessman and Manchester United co-owner are "offensive and wrong".
Manufacturing was the main driver of growth during the final three months of the year, official figures show.
The two victims are said to be in a stable condition in hospital following the attack on Tuesday.
Head of the Civil Service Sir Chris Wormald is understood to be negotiating an exit package from his job.