Did Google Just Wipe Out a Big Law Firm with a Huge Link Penalty?

Top UK law firm Irwin Mitchell just disappeared from almost all search results. They are no longer appearing for even branded terms like Irwin Mitchell, except in paid results: https://www.google.co.uk/#q=irwin+mitchell

Folks looking at the situation tell me this is likely a link based penalty.

Given this is a high-profile law firm, it will be interesting to see how this plays out. Will the legal firm push back with legal action? Was the penalty justified?
Photo
Shared publiclyView activity