(2)Where a party intends to call an expert witness at trial but cannot obtain from him a report, or where, because of the nature of the proposed evidence, the expert is not required by the party to submit a written report, the party may comply with paragraph (1) by serving on every other party a report signed by the party or his solicitor which sets out the name, address and qualifications of the expert and the substance of the evidence which he is expected to give.