This question is NOT about any one country. It is about whether there is an accepted convention about whether former employer countries are responsible for future actions of their would-be retired intelligence officers.
The premise is that spies lie for a living (quite literally). So any designation of spies as "former" or "retired" can always serve as a "cover" unless there is any legal framework precluding this from happening. It can happen even if such a framework does exist, but if such a framework (akin to prohibition on using Red Cross for military transports) were in place, it would make claims that spies are "former" spies more credible.
There is a number of "former" spies who are very active in public life and actively work to change or shape public policy. I would like to know how their claims of not working for their former employers can be evaluated (really, if they can be evaluated).
Here's some examples of "former" intelligence services employees who are active in shaping public policy (and who may or may not be still active members of their former agencies):
- Igor Ivanovich Strielkov, (presumed former) GRU colonel. Reported to be (or to have been) in charge of the Russian separatists in Eastern Ukraine.
- Christopher David Steele, (presumed former) head of the Russia Desk at MI6. Known to be the author of an anti-Trump (often disputed) dossier created in stages through three different commissions by Bill Kristol's son-in-law, HRC Presidential campaign, and the FBI.
- putting this one on this list maybe controversial, but still... Edward Snowden, (presumably former contractor at) the NSA. Snowden revealed existence of NSA's program to collect meta data of most calls made in the US. The construction of the building structure doing the surveillance was known to a very large group of people (some with and some without any clearance) and the building structure is large enough to be visible from space. The revelation of its existence split public opinion (which was uniformly against blanket surveillance) into the anti-surveillance and anti-"treasonous"-Snowden camps.
These are just some of the examples of controversial "former" intelligence services employees. There are many other examples of publicly-active ones which are par for the course.
I realize that I am making claims which many people may wish to contest based on news reports and based on their own views. But, please, keep in mind that most of the "questionable" claims I made are part of the context. The question itself is whether there is any legal internationally-adapted convention against identifying active spies as "former"? And if so, whether these conventions make it incumbent upon their past employers to "rein them in" if their actions interfere with public good of other states after their retirement.