Expert witnesses are required by law to verify their reports with a statement of truth. That duty is set out at Civil Procedure Rules Practice Direction 35, paragraph 3.3.
From 1 October 2020, the rule is changing. The expert witness's statement of truth must now acknowledge that proceedings for contempt of Court may be brought against anyone making a false statement.
The full wording is set out below:
"I confirm that I have made clear which facts and matters referred to in this report are within my own knowledge and which are not. Those that are within my own knowledge I confirm to be true. The opinions I have expressed represent my true and complete professional opinions on the matters to which they refer. I understand that proceedings for contempt of court may be brought against anyone who makes, or causes to be made, a false statement in a document verified by a statement of truth without an honest belief in its truth."