|First appearance||23rd July 1969|
|Last appearance||28th July 1969|
|Number of appearances||2|
|Played by||Laurence Hardy|
Doctor Mackay was the Walker family doctor whom Jack Walker consulted in July 1969 at the insistence of his wife Annie. The two had been shortlisted to run a bar in Majorca but the dogmatic chairman of Newton & Ridley, Sir Hubert Ridley, put a stop to the plan, feeling that the couple were too old. As Jack had undergone a medical for the appointment, Annie got it into her head that his health was the reason for the cancellation and urged him to see his own doctor.
The kindly Scottish man told Jack that he was in sound health and questioned him as to why he was worried. Jack told him about the failed medical and Doctor Mackay told him that Annie refused to accept that Jack's failed application was because he was 68 and she therefore had to latch onto another reason. Annie didn’t believe Jack’s report when he returned home and herself went to see Mackay, who managed to put her mind at rest.