He was retained by ITV on a part-time role reviewing the 2002 season at various points. Walker's autobiography, "Unless I'm Very Much Mistaken", was published in late 2002. He had eight publishers who wanted to put out the book, and he began to compose it in early 2001. Walker negotiated payment of the book sales with the publishers HarperCollins, and he ventured to various worldwide locations to promote it. He competed in Australia's Targa Tasmania tarmac rally road race as navigator to driver Colin Bond in a Toyota Team Racing-entered Toyota Camry Sportivo in May 2003, finishing second in their class and 44th overall. Walker navigated former Grand Prix competitor Chris Amon in a Toyota Camry Sportivo at the Targa New Zealand that took place five months later, where they finished eighth in their class and 114th outright.