Thank you.
I wasn't questioning whether the costing was done properly. If there's a 1.8% difference.... We learned later, though, that by putting a glass roof on it in a televised House of Commons is problematic. Now we have to build an extra screen to block the sun so that the television cameras can work within the chamber. Why not simply put a solid roof on it and avoid the problem of the sun ruining the television quality? I challenge whether there's only a 1% difference between a glass roof over that massive space and a solid roof.
I guess my question is, rather than rush to defend the design decision, are there rational discussions taking place that might change the design to a solid roof?