So who, apart from the Tories, could knock this speech?
It was, as custom dictates, respectful in every way to her predecessor, Douglas Alexander, both for the work he did in the constituency, and for the way that he graciously accepted his defeat.
It talked about her constituency and its attributes including its distinction of being William Wallace's birthplace!... Of course she mentioned its high level of poverty and deprivation.
It discussed the way that people who have already been dealt a poor hand in life have been driven, by the Tory and Liberal government, to a point where they have lost all dignity and broken down crying with utter frustration and misery.
It pointed out that there is one set of rules for ordinary people and one set for the elite, like MPs. Mhairi is 20. She earns over £40,000 a year. Either of these facts would disqualify her from entitlement to subsidised housing (Housing Benefit), were she not one of the chosen few.
The speech praised one of the Labour Party's (and Mhairi's) heroes, Tony Benn, (incidentally a man violently opposed to Scottish independence), dating from back in the day when Labour was a socialist party.
Finally it pointed out the indisputable fact that in the UK parliament, the SNP and the Labour party should be working together against the policies of the Tories, and it offered the hand of friendship to the Labour benches.
Through it all there was sadness and humour and most of all, honesty.
Can you seriously imagine that a genuine Labour supporter could criticise this speech?
And yet... Duncan Hothersall did.
How, you would be entitled to ask, could he be so small?