The man responsible for data protection promotion at the Information Commissioner's Office (ICO), Steven McCartney, at the time Google was cleared of wrongdoing over its Street View mapping system, went on to become the search and mobile software giant's UK privacy head.
This move, which happened last November, has been interpreted by some as a conflict of interest.
The ICO's denied McCartney was involved in the 2010 investigation and therefore there was no conflict of interest.
"Stephen McCartney played no part in the investigation into the Google Street View project while working at ICO," the organisation said in a statement.
Not everyone is happy with that explanation, starting with Conservative MP Robert Halfon.
"This is a pretty shocking revelation. It raises more questions about the Information Commissioner than it does Google because clearly the ICO has been asleep on their watch on this issue. Now it seems they [the ICO] have had a cosy relationship with the company they have been investigating,' he told The Guardian newspaper.
In July 2010, while McCartney was working for the ICO, the organisation decided to accept Google's explanation that Street View's possible capture of private user data such as Wi-Fi access point passwords and Mac addresses was not significant.
In June this year the ICO was forced to re-open the same investigation after the US Federal Communications Commission (FCC) concluded that Google had not only gathered extensive personal data from its Street View cars but had failed to own up to how much it knew about it.
By now McCartney was communicating with his former employer, the ICO, on behalf of his new employer, Google, regarding the same privacy issue.
"The published correspondence between Google and the ICO clearly shows that Stephen McCartney was treated like any other organisation's representative, with his emails receiving nothing more than a polite acknowledgement."
The ICO's head of enforcement, Stephen Eckersley, was currently investigating Google's behaviour, the statement added.
The ICO has come under increasing fire over its handling of a range of often complex issues.
Earlier this week, the ICO was criticised by security company Barracuda Networks for reporting on the issue of unwanted marketing via phone calls and email without mentioning abuse of social media.
The news of McCartney's role change came to light after a freedom of information (FOI) request made by a member of the public