SYDNEY — Australia’s slow march from analog to digital TV has been given a boost.Andy Townend is ankling as topper of Blighty’s digital changeover body, Digital U.K., to do the same job Down Under. Townend will head Digital Australia, which has been set up by the government to speed up Aussie uptake of digital. He takes up his Australia-based post next month. Just a third of households here have made the switch while in Blighty the figure is nearly half. Australia is skedded to change to digital TV from 2010-12, a date that has already been put back from 2008.