Thanks for your reply. It is difficult for a worker to claim on discrimination then if contracts cannot be seen as employer can claim different employees have different contracts.
The employment contract is unlikely to be the source of the discrimination.
Discrimination under the Equality Act is restricted to 9 specific grounds:
Gender
Civil status (married, etc)
Family status (pregnant, parent etc)
Sexual orientation
Religion
Age (does not apply to a person under 16)
Disability
Race
Membership of the Traveller community.
You don't need to see the employment contract to establish this.
An employer is fully entitled to pay one employee more than another employee as long as the grounds for so doing is not one of the above.
The only relevance of a contract that I can think of would be if the contract says "You will be appointed to the assistant accounant role and on retirement of the accountant, you will be appointed accountant". Subsequently someone might complain about that promotion being discriminatory.
Thanks AJ and Brendan. From reading your replies it does not seem to fit as discrimination. It would come under the guise of preferential treatment and when the agrieved workers complained they were advised that the other worker had a different employment contract. This was where the query arose.
There is a union and it may be taken up with them.