Inventive Leisure, the vodka bar specialist, saw pre-tax profits rise by 62% to £940,000 in the six months to December 23.

Overall turnover was up 65% to £8.56m while like-for-like sales at more established outlets were up nearly 6%.

However, operating margins fell 1.4% because of increased business rates introduced in April.

Margins were also hit by a rise in rental costs as Inventive switched to leasehold from freehold sites.

In the first two months of this year turnover was up another 49% year-on-year while like-for-like sales rose by 2.5%.

Chief executive Roy Ellis said Inventive was no longer looking for packages of outlets and was still waiting to find the right site in London at the right price for its Revolution vodka bar brand.

Inventive is about to open its first branches in Newcastle-upon-Tyne next month and Doncaster in June to take its estate up to 28.

Another five bars are already under way across the UK while terms have been agreed on a further seven.

said Inventive was also opening larger sites while keeping fit-out costs unchanged.

New Revolutions in Derby, Bristol and Manchester's Deansgate Lock were an average of 3,600 sq ft, up from the previous average of 2,500 sq ft.

Ellis said total sales of vodka at its Revolution bars now accounted for 31% of all sales,

up 2% year-on-year, while innovative promotions had pushed up sales by 8% on a like-for-like basis.