Travolution has learned TripAdvisor officials in the UK finalised the purchase of 100% of the Holiday Watchdog stock last week for an undisclosed fee.
The deal is a major coup for TripAdvisor in the UK, giving it access to a large user base and a site well positioned as a first port-of-call for many holidaymakers.
Holiday Watchdog attracts around one million unique users each month and is well known for its strong performance in search engine results on major travel-related keywords.
TripAdvisor said it currently has no plans for integration between the two brands.
A fourth site under the EStuff brand, Sunshine.co.uk, will remain with Brown and Clarkson.
Brown and Clarkson will remain with the company during the transition phase but the remaining staff at Holiday Watchdog – understood to number around five – will not be switching to TripAdvisor.
The pair refused to comment on the deal.