I'm often asked what the key difference is between the UUP and DUP. The DUP is ruthless, unemotional, disciplined and well organised.
As soon as the people who matter – by which I mean Robinson's inner-circle – realised that Ian Paisley was becoming a liability, they ditched him. That simple. That brutal.
They needed his imprimatur to seal the deal with Sinn Fein in 2007. Once it became clear 'Chuckle Brothers' was being deployed as a term of ridicule rather than affection; and as he looked and sounded increasingly unsure of himself, they knew they had to cut him loose.
Given the nature of the role – a non-stop diary of photo-ops and smiley soundbites with McGuinness – hiding him from public view wasn't an option.
Jim Allister was on their right flank and the UUP was biting at their heels accusing them of opportunism and hypocrisy.
Some elements of the party and the Free Presbyterian Church (still locked at the hip at that point) were also uneasy. Paisley was now both a media and political problem for them.
He had served his purpose: but now the party needed someone harder and less McGuinness-friendly to settle the nerves. In those circumstances getting rid of Paisley was the right thing to do. Indeed, it's what he had helped to do to O'Neill, Faulkner and Trimble.
It's what he would have done had he been in Robinson's shoes. And it also paid off for Robinson. The DUP saw off the challenge from Jim Allister in the 2009 Euro election; won its highest ever number of seats at the 2011 Assembly elections; and widened its lead over the UUP.
Ditching the Doc made strategic, electoral, political and media sense.
It is worth bearing in mind, though, that if the fallout from the Paisley programmes damages the party at the Euro/ Council elections in May, the DUP may ditch Robinson too.
He, more than anyone else, knows that.