It transpires he got a member of the team to do a task without the permission of his managing director, when working on the TfL’s engagement with the London Assembly.
He says: "To be honest I was making it up as we went along so he might have been right that I shouldn’t have, but, sending a memo…"
Now director of comms at the Electoral Commission, the independent body set up by Parliament to maintain integrity and public confidence in the UK’s democratic process, Robertson is at the helm of a team of people with big responsibilities.
Despite its challenges, Robertson enjoys his role as a comms leader.
He says: "I love it. Never a dull moment and there’s a chance to make a real impact on people’s lives."
After joining the commission in 2008, Robertson rose through the ranks to become comms director in October 2010, just months before the ‘Alternative Vote’ referendum in May 2011; an event that proved to be one of the biggest challenges in his career so far.
Yet Robertson seems to have taken it all in his stride.
He says: "If I’d been worried about getting everything right I’m not sure I’d have slept for nine months. You take a lot from times like that."
The increasing pressures of smaller budgets and the looming prospect of the EU referendum, which Robertson says is "going to be interesting", are just some of the demands in his current role.
He adds: "The need to prove cost-effectiveness is also an issue now in a way it wasn’t ten years ago."
The recent general election raised specific problems of its own, including the challenges of running an ambitious large-scale campaign.
Robertson explains: "We set ourselves a huge target for the campaign – getting a million additions to the electoral register – and that meant taking risks we hadn’t taken before, particularly working with partners."
The comms department also faced external pressures.
He says: "There was also a lot of political scrutiny and concern from outside the organisation – as well as a fair amount inside – about whether we were doing enough".
Robertson notes that this focus on end success has developed into a trend since he first started in the comms industry.
He says: "It’s part of a much sharper focus on rigorously interrogating what you’re doing and looking for measures of success based on outcomes."
For Robertson, pushing through to meet the ‘outcome’ is one of the key lessons for people in the industry to learn.
He says: "People in communications like to focus on being great ‘communicators’ and coming up with fantastic ideas, but if you can’t turn an idea into reality and persuade your organisation to do what you suggest you’re only doing half your job."
The attitude appears to have paid off. Robertson reveals that, in the lead up to the general election, his team exceeded the one million target, with 1,561,000 additions to the electoral register.
Robertson will be one of the key speakers at PRWeek’s Leaders in Communications event in November, where he will cover "Trying something new, taking risks and the power of data".