With reference to the "link" provided by Carnkie to the list of buildings that used Portland stone, that is found on Wikipedia. There is a glaring mistake in the reference under "Memorials" which states "All grave stones for British personell killed in the First and Second World War are made out of Portland Stone". This information is incorrect, as the order was placed by the Government with a famous Derbyshire quarry, i.e. Hopton Wood Stone quarry sited near Middleton-by-Wirksworth to supply the gravestones which are in fact made of Carboniferous limestone and not Jurassic as the Portland limestones are. Also in this quarry was found one bed of pure marble (i.e. limestone metamorphised by volcanic heat to marble). Work at this quarry ceased in the late 1940's about 1948/49 time.
Roger the Cat - about 1964 with my ex and Dr. Trevor Ford (PDMHS and Leicester University) we explored a tiny stone mine at Stonesfield in the Cotswolds, it was shallow workings, accessed by a small shaft approximtely 20/25 deep, it dropped into a small chamber with no workings off, and had obviously been mined for stone for slating roofs in the locality. Trevor thought that this was how the village got the name of Stonesfield. Afterwards Trevor wrote an article about this mine (from memory I think it could have been in a Cave Research Group publication) and around the same time published a detailed report (again I think a CRG publication) on the quarries of Portland Bill in Dorset, of which I have a copy. Portland Bill is worth spending a day on exploring, not only does it have quarries inland and on the the cliffs from where the stone was loaded onto boats, but there is the Portland Museum given by Dr. Marie Stopes (who incidently was a Doctor of Geology) with it's stone collection, and the church of St. George's (now closed and only open at Xmas and St. George's Day 23rd April for services)with it's graveyard and wonderful carvings on the tombstones.