Sir Thomas Bingham MR said,

“In some jurisdictions the forensic tradition is that judges sit mute, listening to advocates without interruption, asking no question, voicing no opinion, until they break their silence to give judgment. That is a perfectly respectable tradition, but it is not ours. Practice naturally varies from judge to judge, and obvious differences exist between factual issues at first instance and legal issues on appeal. But on the whole the English tradition sanctions and even encourages a measure of disclosure by the judge of his current thinking. It certainly does not sanction the premature expression of factual conclusions or anything which may prematurely indicate a closed mind. But a judge does not act amiss if, in relation to some feature of a party’s case which strikes him as inherently improbable, he indicates the need for unusually compelling evidence to persuade him of the fact. An expression of scepticism is not suggestive of bias unless the judge conveys an unwillingness to be persuaded of a factual proposition whatever the evidence may be.”
[ 356 a – c]