The young son of Charles Kennedy has watched tributes from across the floor of the Commons to his late father from MPs.

Ten-year-old Donald watched with his mother Sarah, Mr Kennedy's former wife, from a gallery above the Commons chamber as Prime Minister David Cameron and Liberal Democrat leader Nick Clegg pay tribute to their former opponent and colleague

Several MPs, including LibDem leadership candidate Tim Farron, spoke directly to the boy in the gallery above.

Mr Farron, who hopes to succeed Mr Clegg as leader of the party, addressed Donald directly looking up at him from the floor of the house.

He said: "You should be really proud of your daddy. I am proud of your daddy. I loved him to bits and I am proud to call him my friend. God rest you, Charlie."

The young lad - who has inherited Kennedy's boyish looks and red hair - was seen to smile and glance into his mother's eyes as MPs shared fond memories of his dad, who outgoing Liberal Democrat leader Mr Clegg said would want to be remembered as "a kind and loving father, brother and son first; and an accomplished politician second".

As MPs, many wearing dark ties, listened in respectful silence, there could be no doubt of the genuine affection in which Mr Kennedy was held.

He was praised for his courage in standing up against the war in Iraq and his success in leading the Liberal Democrats to their greatest ever electoral results.

But there were also copious tributes to his charm, his wit and his ability to relate to ordinary people who took no interest in politics, or were even actively hostile to politicians.

Mr Cameron quoted Kennedy's close friend Alastair Campbell as saying that he "spoke fluent human, because he had humanity in every vein and every cell".

He said he was the "most human of politicians" and - at his best - "the best that politics can be".

Mr Clegg hailed his predecessor as a "formidable parliamentarian", but sparked laughter as he recalled that Kennedy viewed policy detail much as he viewed the mountain Ben Nevis which towers over his Fort William home - as "something to be admired from afar, but a trial to be endured by others".

His troubled relationship with alcohol was mentioned only fleetingly, Mr Clegg describing him as "brave yet vulnerable, brilliant yet flawed ... a fully paid-up member of the human race".

The sombre atmosphere following Kennedy's death overshadowed the first session of Prime Minister's Questions of the new Parliament, which might otherwise have been a boisterous event, with Conservative and Scottish National Party MPs fresh from their election triumphs.

The SNP's leader in Westminster Angus Robertson made a point of prefacing his first question with a few words in Kennedy's honour, and took a notably measured and statesmanlike tone as he quizzed Mr Cameron on the plight of migrants trying to cross the Mediterranean by boat from Libya.

And there was a display of reserve from SNP MPs, who have ruffled a few feathers in Westminster by applauding speakers in the chamber and jostling for seats. Veteran MP Dennis Skinner claimed his usual front-row spot alongside the aisle without a struggle, though there was some Labour annoyance at the presence of a few SNP MPs on the bench behind their acting leader Harriet Harman.

As leader of the third party in the Commons, Mr Robertson has been granted an automatic right to two questions at each session of PMQs, and some observers expect this to give a decidedly Scottish flavour to proceedings.

But his choice of subject appeared to indicate an intention to engage in areas well beyond the confines of Scottish politics and assert the SNP's position as a player on the national and international stage, as well as a readiness to outflank Labour to the left on issues like immigration.

Ms Harman made an attempt to pin Mr Cameron down on his intentions on welfare, but the Labour ranks - reduced from 255 to 238 by the May 7 election - seemed subdued as they contemplated a further five years in opposition.

Still, the Prime Minister had cheering news for one of them - incoming Lancaster and Fleetwood MP Cat Smith, who he picked out as a potential future leader after her first ever PMQs question.

When the 29-year-old, who was one of only a handful of Labour MPs to win a seat from the Tories at the election, challenged the PM over when Britain would regain its AAA credit rating, Mr Cameron responded that her question showed "a sign of progress" from Labour on the economy.

"There's a leadership contest on, " he told her. "I would throw your hat into the ring. In that one question, you made more sense than the rest of them put together."

It is doubtful that the praise was entirely welcome to the new Labour MP, and it was a rare moment of traditional PMQs knockabout on a day when Westminster's thoughts were with a politician whose non-adversarial style made him stand out from the Punch-and-Judy politics which often dominates the House.