Politicians and business people should know by now that no comment that they make is 'secret, 'behind closed doors' or 'off the record'.
There is always someone willing to break a confidence, take footage on a mobile device or invite people to attend who really should not be there.
Even the selection of location can be a problem. Recent meetings of the Parliamentary Labour Party are said to have taken place in rooms that journalists can peer into.
Once the information is out there - across all forms of media - then the damage is done. It is very difficult to fight back but reputations should always be rebuilt.
If only the time and effort had been invested early on.
The prime minister caused controversy on the eve of the vote by labelling Mr Corbyn and other opponents of action as "terrorist sympathisers". The BBC's political editor Laura Kuenssberg said the comments were a departure from the "carefully crafted" language that Mr Cameron has used over the past week.
