Is there a rule or decided case which establishes that witness statements cannot introduce facts to prove matters that are not particularised in the statement of case?

This Q&A considers whether or not a party will be entitled to rely upon facts included within a witness statement to prove certain matters, where those facts have not been included within the party’s statement of case. As a general rule, all material facts relied upon, ie those that are necessary to frame the cause of action and establish a party’s right to the remedy sought, must be pleaded if they are to be relied upon. A witness statement cannot simply cure any deficiencies within a party’s pleaded case. 

In this scenario, the crux appears to be whether or not a party will be entitled to rely upon facts alleged within a witness statement, where the issues to which those facts pertain were not included within a party’s statement of case.

While the requirement pursuant to the CPR for disclosure and the exchange of witness statements has arguably