Theresa May’s relationship with Angela Merkel is “almost non-existent” after six months in Downing Street, The Telegraph has learned.

The apparent failure of Mrs May to engage the German chancellor is causing mounting concern in Whitehall as British negotiators gear up to trigger Article 50 and begin EU divorce talks in less than three months' time.

The dismay among officials emerged amid a growing row over the resignation of Sir Ivan Rogers, the UK's top diplomat in Brussels, who quit this week warning of "muddled thinking" over Brexit.