How effectively can an English employer restrict an employee's activity after the employment ends?

Essay from the year 2009 in the subject Business economics - Law, grade: 1,7, Schmalkalden University of Applied Sciences, language: English, abstract: If an employee change his emploeyer, there is the danger, that the ex-employee takes the company secrets and other interesting and confidential information with itself away to his new employer, who is very likely a competitor of the ex-employer or the ex-employee uses his knowledge to settle his own undertaking and than competes with his former employer.

So there is a big interest on the part of the ex-employer to restrict the possibilities of the Information transfer to the competitor by the ex-employee. It is arguable how and in which complexity it succeeds, in relation to English law and to European law. This should be illustrated in the following.