Re: So Simon once worked at one of my old employers!
Previous employer; around the early 2000's - dictate from on high - we were not to fill in time sheets during work hours on a customer site; but since that described 95% of the team's normal work pattern this meant we had to do it at some other time i.e. when at home.
Then another dictate - the 3 minute daily (mobile) phone calls allowed when away from home must be extracted from the company mobile phone bill and itemised in our expenses.
I managed to get both instructions written in an email as being part of our normal duties.
A couple of months later; my very good manager had to haul me over the coals for excessive Sunday overtime claims. He happily joined me in escalating this up 2 or 3 layers of management.
Why was I doing the mobile phone and time keeping on overtime ? Answer : because you have explicitly instructed us to fill the time sheets in weekly and we are not to do them on site. See this email trail. As a company imposed duty I am entitled to claim overtime.
Why am I always doing that on a Sunday ? Because since I have to do it on my own time I get to decide when it is convenient to do so.
HR (by now involved) started to speak; then stopped; thought it all through; the senior management person started to shout; HR stopped him; and suggested to management that they either put up with the overtime claims being done at the engineer's convenience; or allow us to do the timesheets during normal working hours; and as for the average £10 per month mobile bill just forget it; the cost of processing the paper work far exceeded any possible benefit especially as local management already had the costs under good control.
Unhappy senior manglement - happy engineers (well apart from losing a couple of hours Sunday overtime a month) - manager's manager couldn't hid his grin but did control his urge to laugh !
Sometimes HR can be sensible and a good manager is worth his weight in gold