Who is responsible for paying income tax
If your employer pays you directly, they are responsible for paying income tax through the PAYE system.
If all the tips are combined and shared with each other, it is called "tronc". the person who oversees this process is called "troncmaster", and he is responsible for the payment of income tax.
In case your employer decides how to distribute the tip, national insurance must be paid as well as tax. Your employer is responsible for ensuring payment through PAYE.