LONDON (Reuters) - British Prime Minister Theresa May should call a leadership election and as many as 30 of her lawmakers support telling her to go, former Conservative Party chairman Grant Shapps said on  Friday.  I think she should call a leadership election,  Shapps told BBC Radio 5 live.  The writing is on the wall.  Shapps, who chaired the party between 2012 and 2015, said up to 30 Conservative lawmakers backed the bid to tell May to go. 