Sports Direct’s founder Mike Ashley has challenged the authority of a parliamentary select committee by refusing to appear before MPs investigating pay and working conditions at the retailer, despite being formally summoned. The riposte, in which the billionaire called the parliamentarians “a joke”, is the latest instalment in an increasingly bitter battle between Ashley and the Commons’ business, innovation and skills (BIS) committee, which took the unusual step of issuing a summons...The inquiry by the committee, which has threatened Ashley with being in contempt of parliament if he fails to attend a hearing on 7 June, follows a Guardian investigation last year that found workers at the sportswear group’s Shirebrook warehouse were receiving, in effect, rates of pay below the minimum wage...Ashley said he would challenge the formal order and accused the MPs of “showboating”. He said they cared only “about the business of politics, while I actually care about the people at Sports Direct”.