Figures compiled from data from Children's Information Services show an average weekly national cost of 77.34 for holiday childcare, a rise of nearly 10 a week over the past three years.
However, costs for inner London have dropped significantly - to 48.90 per week - because a number of boroughs in the capital now subsidise provision.
Outer London shows the highest average cost, at 90.28 per week.
Joint chief executive of the Daycare Trust, Emma Knights, said, 'The reduction in childcare costs for inner London is good news for parents. It shows that when local boroughs invest and subsidise childcare costs, there are real and tangible benefits for local people. It would be even better if other councils were to follow suit, thereby lowering the national average for holiday childcare costs as they are still far too high.'
Full survey results can be found at www.daycaretrust.org.uk.