Baroness Thatcher would be "humbled" that the Queen is attending her funeral, her son has declared as he spoke of her death for the first time.
Sir Mark Thatcher gave a statement on the steps of the former prime minister's home in London after flying in to help arrange next week's ceremony.
He said his mother had been blessed with "a long life, and a very full one" but that her death was "without doubt a very sad moment".
He also expressed gratitude for the messages the family had received "from far and wide", which he said would be a source of strength in the days ahead.
Margaret Thatcher died on Monday
Sir Mark is the first member of the family to speak publicly about Lady Thatcher since she died on Monday at the Ritz in central London.
His statement came moments before a special Parliamentary session allowing MPs and peers to pay tribute began.
In it, Prime Minister David Cameron paid tribute to Lady Thatcher, describing her as an "extraordinary woman".
He said: "She made the political weather, she made history and - let this be her epitaph - she made our country great again."
Lord Tebbit, one of Lady Thatcher's key allies in Cabinet and her former party chairman, paid an emotional tribute for the support he received after he and his wife were injured by an IRA bomb in Brighton in 1984.
He said: "She was brought down in the end not by the electorate, but by her colleagues."
More details were released about her ceremonial funeral, which will be held next Wednesday at St Paul's Cathedral.
The Queen and the Duke of Edinburgh are breaking with protocol by attending the service, which is not an official state ceremony.
Tony and Cherie Blair will be at the funeral next week
Sir Mark said: "I would like to say how enormously proud and deeply grateful we are that Her Majesty has agreed to attend the service next week at St Paul's and I know my mother would be greatly honoured as well as humbled by her presence.
"By any measure, my mother was blessed with a long life and a very full one. However, the inevitability or the inevitable conclusion may appear of the recent illness that she suffered, it is no easier for us to bear in what is without doubt a very sad moment.
"We have quite simply been overwhelmed by messages of support and condolence of every type, from far and wide, and I know that my mother would be pleased they have come from people of all walks of life."
He said many of the messages contained personal stories related to "the journey of my mother's life".
Former ally Lord Tebbit paid an emotional tribute in the House of Lords
"We are all enormously grateful for the warmth that these messages convey and they will be a source of encouragement and strength as we face the inevitable days ahead," he said.
Britain's longest-serving prime minister and the only woman ever to hold the role is being given a ceremonial funeral, one below a state occasion.
More than 700 members of the armed forces from all three services, including those with links to the Falklands war, will take part.
A public holiday has been declared on the Falkland Islands next Wednesday to allow people to watch Lady Thatcher's funeral and to attend a memorial service in Stanley.
Members of the Honourable Artillery Company will fire procession minute guns from Tower Wharf at the Tower of London.
Representatives of all three services will also line the funeral route, while three military bands play - their drums draped in black as a mark of respect.
A huge security operation costing millions is expected in central London during the ceremony amid fears of protests and disruption.
Lady Thatcher's estate will contribute but the rest of the money will be provided from the public purse.
Downing Street is refusing to give details of its total cost ahead of the service and ministers have defended the expense.
Foreign Secretary William Hague said: "The rebate she negotiated for this country from the EU has brought us so far £75bn - which is twice the size of our annual defence budget.
"I think that puts money in perspective ... so I think we can afford to contribute to a funeral."
Plans for the ceremony have been dubbed Operation True Blue and Lady Thatcher is to be given full military honours.
Units linked to the Falklands war will play key roles at the ceremony
Tony Blair and his wife Cherie as well as Gordon Brown and his wife Sarah will be at the ceremony, which will be one of the largest public funerals of recent decades.
Lady Thatcher's coffin will be transferred to the Chapel of St Mary Undercroft in the Palace of Westminster on Tuesday ahead of the ceremony.
There will be a short service following its arrival before the coffin rests in the chapel overnight.
The streets will then be cleared for a procession taking the former leader's body from parliament to Church of St Clement Danes, the RAF Chapel on the Strand.
At the church, it will be transferred to a gun carriage drawn by the King's Troop Royal Artillery.
The streets will be cleared for the procession on to St Paul's and members of all three services will line the route, as well as bands from each.
The Gun Carriage will be drawn by six horses, three of which are mounted, with a sergeant riding alongside, an officer riding in front and three dismounted troops on foot.
A Bearer Party made up of all three services will walk alongside the coffin, and will include those from ships, units and stations notable for their service during the Falklands campaign.
Outside St Paul's there will be a Guard of Honour of 1st Battalion Welsh Guards, as well as the Welsh Guards Band.
For the coffin's arrival, there will also be a Step Lining party made up of 18 personnel from all three services.
These will include six Navy, six members of the Blues and Royals, Household Cavalry Mounted Regiment, and six RAF, plus Chelsea Pensioners of the Royal Hospital Chelsea.
Ten members of staff from the Ritz, where Lady Thatcher had been staying since Christmas, have also been invited in recognition of the care she received at the hotel.
The public will not be able to attend the funeral service itself but will be able to line the route of the procession.