Britain's youngest MP has spoken of her frustrations at some of Westminster's traditions, saying it must decide whether it is a museum or a functional parliament.

Mhairi Black, who as a 20-year-old student was voted MP for Paisley and Renfrewshire South in May amid a wave of SNP dominance in Scotland, received widespread praise for her maiden speech in the House of Commons during the Budget last week.

Despite her early success, she says she is still getting used to some of the intricacies of Westminster, and that some of its foibles grate on her.

Ms Black said she thinks the rule of no clapping in the House is senseless, saying: "So you're not allowed to clap like an ordinary person, but you're allowed to bray like a donkey?

"I mean, see PMQs, especially the Conservative side, they've got this weird noise they do. It actually sounds like a drunken mob."

Westminster must choose, she said, whether it is a museum or a functional parliament, saying: "It's constantly swinging between the two, and quite often they are at odds."

She also suggested the tradition of having to vote in person, rather than electronically, is outdated.

"Are we genuinely saying that the Underground can log millions of travellers, day in, day out, without a problem, and 650 of us can't hit a button?

"It's just stupid. A couple of Mondays ago, I didn't get home until half past midnight because we were voting. How is anybody with a family supposed to work those hours?"

Ms Black admitted the moments she hates most at Westminster are those in the chamber, where "you just hear folk talking so much guff".

And she said she thinks the union is doomed, that Scotland was giving the British parliament once last chance with its referendum result last September.

She said: "I'd have another referendum tomorrow, but it's not up to me. It's up to the people of Scotland, and I think people are finding their feet and they're finding their confidence."