Bus and train group Go-Ahead's chief executive Keith Ludeman is to retire after 15 years with the company to be replaced by David Brown, currently TFL's Managing Director, Surface Transport.The group added that trading in the period to end October has been robust and it has not changed its expectations for the full year to 2 July 2011. "The Comprehensive Spending Review should have no direct impact on the group in the current financial year and at this stage we believe that we can manage any impact on our results in following years through a combination of further cost savings and recovery through fares, " it added.On its bus side outside London, like-for-like deregulated passenger numbers were up around 3% and revenue up around 4% in the quarter compared to last year, with the majority of the growth coming from fare paying passengers. In London, like-for-like regulated mileage for the quarter was around 1% above the equivalent period last year. Revenue, including QIC incentive income, was slightly better than expected, but 7% below the equivalent period last year following the start of new contracts from January 2010.Revenue picked up across all three of Go-Ahead's rail franchises. Southern's revenue increased by over 6% consisting of a small reduction in Gatwick Express more than offset by good growth on the mainline services. Southeastern revenue grew by over 10% against a weak first quarter last year. London Midland revenues rose by 7% as the number of passenger journeys increased by 4%.