I am open to correction on this but as far as I can see from the CRB website those who are exempted from the Rehabilitation of Offenders Act and can therefore be the subject of CRB checks would be (inter alia) Solicitors and Legal Executives. I cannot see that there is any general provision applicable to people who work in Solicitors' firms and would therefore query the basis upon which there can be a requirement for CRB checks for all employees working in conveyancing.