Thanks everybody. I am only just seeing these replies as I have been sidetracked by a non Volvo issue
It is the part you identified 142, and the replacement bearing, washer and circlip are items 30, 31 and 32 on your diagram. I think that 29 must just be (one of six) flywheel bolts rather than a centrally located bolt as indicated.
And Blue, there is indeed space to get a small puller leg in behind, but only one and I don't (currently!) have a slide hammer.
So Fart's hydraulic method is what I will be trying as soon as I can get back under the car. And I will keep the toilet paper handy, Austin.
And no worry about blow-through Ron. The bit I am trying to remove is just a solid spacer, not a bearing, but I do see your concern.
Thanks again everyone!