The Queen and the Duke of Edinburgh will celebrate their 60th wedding anniversary with a service at Westminster Abbey on Monday.

Some 2,300 people are expected to fill the Abbey for the service, including many members of the Royal family.

After the service, which includes a reading from grandson Prince William, the Queen and Duke will unveil a new Jubilee Walkway plaque in Parliament Square.

On Sunday, Prince Charles hosted a dinner at Clarence House in celebration of the Queen and Duke's diamond anniversary.

Later in the week, the Queen will make her first ever visit to a specialist Christian Aids clinic and children's hospital in Uganda.

The UK-based Christian Aids charity, Mildmay, will show the Queen around its pioneering care programmes in Kampala.

The centre was created at the invitation of the Ugandan Government in response to escalating cases of HIV and Aids and the need for specialist care and training programmes to alleviate the impact of the disease.

It consists of outpatient referral clinics, opened by the Princess Royal in 1998, and an international study centre, opened in 1999. The clinics currently provide holistic care for over 5,000 men, women and children who suffer from the complex, ongoing and distressing conditions associated with HIV and Aids.

The Queen will also take in a visit to the newly expanded Mildmay Paediatric Care Centre in Uganda, which offers a number of specialised and innovative services for children, including holistic day care to rehabilitate children living with severe or persistent problems related to HIV and a 53-bed hospital.

The visit from the Queen forms part of the royal itinerary linked to the state visit to Uganda and Commonwealth Heads of Government Meeting, which takes place from 21-24 November in Kampala. The Queen will be accompanied by the Duke of Edinburgh.

The landmark tour will be widely applauded as a significant show of support for those living with and affected by HIV and Aids.

Her Majesty will be invited to unveil a plaque for the children's hospital's new Elizabeth Ward, named in her honour. She will also receive a warm welcome by children who are mounting a fashion exhibition of clothes they have themselves made from locally produced bark cloth as part of their rehabilitation process. The Queen is also due to meet a 'Jajjas' (grandmothers) support group.

"We are absolutely thrilled that the Queen will be honouring Mildmay with a visit to our Aids programmes in Uganda," says Baptist Dr Veronica Moss, the charity's UK-based chief executive, who will be there to welcome the royal party.

"It will be a privilege to show her something of our inspiring work in transforming the lives of sick and orphaned children and adults. Our patients and staff are very excited at the prospect of seeing her."