Control of education and limits on advertising seem to be the most common barriers to competition. Mr. Gray of Indecon found very severe restrictions on competition between solicitors, extensive restrictions on competition between barristers, a number of extensive restrictions affecting competition between doctors and significant restrictions on competition between vets and dentists. As already stated, it found relatively few restrictions to competition between architects and engineers. Regarding opticians, he said there were a number of restrictions which had a potentially negative effect on competition.