Newsagent chain WH Smith announced the retirement of chairman Robert Walker as it revealed a 4% fall in like-for-like sales in the 14 weeks to June 5.Like-for-like sales were down by 4% in both the High Street and Travel divisions, with like-for-like sales at travel outlets down by 2% excluding the impact of the volcanic ash cloud that grounded flights across Britain. The company, which has 569 High Street shops and 495 travel outlets said that, while air passenger numbers remain soft, it has continued to outperform.'The economic environment remains uncertain and whilst we continue to be cautious about consumer spending, we remain confident in the outcome for the full year,' the company said.Outgoing chairman Robert Walker will be replaced as chairman by Walker Boyd, who rejoined the board of WH Smith on 1 February, on 1 September.