The chair of the national coronavirus test and trace system says it is getting ‘better and better’ and local contact tracers could start knocking on people’s doors.Baroness Dido Harding said the £10 billion programme – which is designed to track people who have been in contact with positive Covid-19 cases – is currently ‘working well’.She added that she ‘refused to apologise for spare capacity’ after the Guardian reported that contact tracers were only making a ‘handful of calls a month’.It was