It may seem futile - it may even be futile - but all MPs are sensitive about keeping their jobs, so even if your MP is as useless as a dog turd, she will still notice - and have to think about it - if she gets a lot of correspondence flooding in to her office. These things do get reported back, through the whips and other channels. Boris may never see your letter, but you can bet your bottom dollar he'll know if his MPs are getting hundreds of complaints.
So, don't think "For whatever good it would do" - look on it more like one more nail in the coffin. Whether they'll be enough nails, who knows, but ..............................
Agreed - that's precisely the reason I did it. As a whip herself, she has a slightly shorter route through the chain of command, so who knows...?
She has a pretty thin majority here in Lewes, so she has more reason than most to worry about the long term damage to her job prospects (it's a shame we're such a long way off being able to vote her out).
I mentioned I have a garden, so she will doubtless think I'm a dyed in the wool Tory whose vote she needs to keep hold of...