But the parliamentary bible, Erskine May, makes clear peers cannot be forced to give evidence to Commons select committees.

BBC: Birt warned of 'knock at door'

Erskine May, the Commons' procedural bible, clasped to their bosom, bewigged, bejewelled, bepomped, they hang on to traditional forms like the most Luddite of trade unionists as a cover to protect their otherwise redundant jobs.

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The parliamentary bible, Erskine May, makes it clear that witnesses who "give false evidence, prevaricate, present forged or falsified documents... or attempt in any way to deceive a committee... may be reported to the House and dealt with as determined".

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