Yesterday the Speaker made this brief statement -
Once criminal proceedings are active by a charge having been made, cases before the courts shall not be referred to in any motion, debate or question. The House will be aware that charges have been made against three Members of the House and that therefore the sub judice rule applies to their cases. The matter is therefore before the courts, and the House and Members would not wish to interfere with the judicial process, risk affecting the fairness of a criminal trial or, furthermore, prevent such a trial taking place.
A Standard Note from the House of Commons Library (which can be accessed here) gives the background to the rule.