I work on a small team (approximately 10 people) within a very large company. Within our team, we all share the same line manager and all sit in close proximity to one another, within our office. We're all contracted to work 37.5 hours a week, though I have began to notice that a colleague of mine definitely does not work these hours.
Let's call her Sarah. Both myself and Sarah begin work at 08:30am and finish at 16:30pm, including a 30-minute lunch break that would equal 7.5 hours a day, and 37.5 hours a week. However, Sarah takes hour-long lunch breaks, and yet will still finish her day at 16:30. Our line manager takes even longer lunch breaks, leaving before Sarah does and arriving back after her, and so is unaware of her longer breaks. Just to clarify, we're allowed long lunch breaks, as long as we make up the extra time at the beginning/end of the day, as our hours are flexible.
In addition to this, I've frequently noticed Sarah on her phone, browsing social media or online shopping on her PC. Quite often, she will even grab my attention to come and look at an interesting post she's seen (not very discreet at all). Our seating plan in the office means that I am the only other person aside from Sarah, who can see her screen/desk area, and the only one who can see her procrastinating.
I'm almost certain that our Line Manager is unaware of Sarah's actual working hours. Each week, we record how many hours we've spent working on particular projects for particular clients; to which they get charged for. This means that Sarah has essentially been charging clients for work she has not been doing; and rather charging for her long lunch breaks and un-work-related internet browsing.
I feel as though this is completely wrong, but am very unsure of how to approach my line manager about this behaviour without sounding petty/without Sarah overhearing; I don't want to cause any sort of conflict, as I do have to work with this person on a daily basis. Is this my place to speak up or should I hope that our line manager will notice? How would I go about speaking to my line manager about this?
Side note: I have looked at both of these previously asked questions (here and here). I would say that my question addresses a different issue to both of these. In the first question, the boss is aware of the issue with the colleague, unlike in my situation. The second question relates to the lack of effort given by a colleague. In my situation, yes, the social media browsing and online shopping could relate here. However, an extra 30 minutes, sometimes more, on a lunchtime and claiming it to a project isn't "lack of effort"; it's lying to the company and the client. Some of our clients are charged £50+ per hour of our work, that's £250 a week and £1000 a month they're paying for work they think Sarah is doing, when she's out having lunch.
I agree that I should do my job and let my line manager do their job. But when I'm fully aware that Sarah is claiming for hours she isn't working, and am aware that my line manager doesn't know and probably won't find out without my input; I feel like I'm stuck in a difficult situation. This is costing clients thousands of pounds, I'm aware of the situation and yet feel as though it isn't my place to speak up.