I've been round the nearly-completed insides of it now, with Sir Michael and Lady Patti Hopkins. It's clubbish, conservative, exceptionally well made, and to last: 200 years is the estimate, when your average office block is cynically built to last only 30. I've been coming to terms with its outside for the best part of just one year. It is so solid, so heavy, the antithesis of the lightweight, glassy, high-tech look. Then there are those quasi-industrial chimneystacks, which I have heard compared (by one very powerful figure in the built environment) to the chimneys of Nazi death camps. A ludicrously over-extreme reaction: but it does show how deeply some people hate Portcullis House. The real test comes in October, when 224 MPs and their many staff return to Westminster and move into their new offices.

The chimneys are air vents - the whole building is naturally ventilated, not hermetically sealed and air conditioned. Visually, they respond to the chimneyscapes of, to the north, the Edwardian buildings of Richard Norman Shaw and, to the south, the turrets and finials of the mid 19th century Palace of Westminster by Barry and Pugin. That too has a black roofscape, though behind stone parapets. But nobody could pretend that Hopkins' chimneys are elegant. From some viewpoints they look fine - one of the best views being from the new rooftop restaurant in the National Portrait Gallery - but from others they are over-dominant. Me, I find them interesting because, like the whole of the building inside and out, you can see exactly what they are and what they are doing. The building is a self-explanatory diagram for those who care to study it, a subtler version of Richard Rogers' Pompidou Centre in Paris.