Yes. Following a series of important court rulings brought by unions, it is now established that holiday pay must be your 'normal' wages. This means it must include all the pay components you would normally have earned had you not been on holiday.
This includes, for example, all regular overtime, travel time payments, shift or weekend premium payments and anti-social hours payments.
It is unlawful for your employer to pay you holiday pay based on basic pay only, excluding your overtime. Speak to your union if you are concerned about how holiday pay is calculated where you work.
Strictly speaking, the rulings referred to apply only to the four weeks of holiday given to workers by the European Working Time Directive, but a good employer is likely to apply a uniform policy of calculating holiday pay across your full holiday entitlement.