"He shouldn't have to do this, there should be an executive in place but without one London is clearly going over our heads." SDLP MLA Claire Hanna on David Sterling's leaked letter to Downing Street

In a dramatic intervention, the head of the civil service here, David Sterling, has warned the government that it's plans for the border post Brexit fail to solve most of the problems. In a private letter to Downing Street, Mr Sterling also appears to criticise a lack of engagement between officials in London and their counterparts in Belfast. He then lists seven areas in which he says Whitehall has not been taking advantage of local knowledge. These include trade and north-south co-operation. So what is going on? Are the plans of the go vernment and their partners, the DUP, fatally flawed or is this a civil servant acting above his station?