Dear Bhowmick,
I find a mismatch regarding the nature of engagement of the individual's services between the title of the query and its inputs. The expression "he had an appointment letter and his position was 'Purchase Head'" along with the detail of his joining in 2012 at the age of 61 indicates that he has been employed as a regular employee in the organization. Under the current labor laws, the age of an individual, other than a child, is not typically a restrictive factor against employment unless the minimum and maximum age for appointment are strictly prescribed in the organization's service regulations. Therefore, appointment at any age beyond the age of superannuation cannot bar the right to claim gratuity if other conditions are fulfilled by the concerned employee.
Nowadays, the nomenclature 'consultant' is very loosely used in sectors like IT and ITES, whereas the original meaning of the term consultant implied engagement of a specialist on a retainer basis under a specific contract for service.