The reason you can't go too close to the end is that the shear load is greatest there.
If they are 55mm wide that's an odd size but it will help with the shear strength.
You could go to a structural engineer and get them to calculate if you're worried
They are old imperial size joists, so I might have rounded the dimensions inaccurately, but so much else in these houses is "interesting", I would not be surprised that they are wired sizes
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