(1) For the purposes of this Part an employee shall, subject to this Part, be taken to be dismissed by his employer if but only if -

(a) the contract under which he is employed by the employer is terminated by the employer, whether by or without notice, or

(b) where, under the contract under which the employee is employed by the employer the employee is employed for a fixed term or for a specified purpose (being a purpose of such a kind that the duration of the contract was limited but was, at the time of its making, incapable of precise ascertainment), that term expires or that purpose ceases without being renewed under the same or similar contract, or

(c) the employee terminates the contract under which he is employed by the employer in circumstances (not falling within subsection (5)) such that he is entitled so to terminate it by reason of the employer's conduct.

(2) An employee shall not be taken for the purposes of this Part to be dismissed by his employer if his contract of employment is renewed, or he is re-engaged by the same employer under a new contract of employment, and -