Senior royals from around the world are gathering Tuesday for a memorial service for Prince Philip at Westminster Abbey that will incorporate hymns and other touches dropped from his funeral last year because of the pandemic.

Queen Elizabeth II will attend the service of thanksgiving, Buckingham Palace said. The 95-year-old monarch was deeply involved in planning the event, but she has experience unspecified mobility issues in recent weeks and her presence at the event was unclear.

Elizabeth, who recently recovered from COVID-19, didn’t go to a Commonwealth Day service at Westminster Abbey earlier this month, but she continued with other scheduled engagements, including in-person audiences.

About 1,800 family members and guests have been invited to the memorial. Only 30 people attended last year’s funeral, conducted under the strict COVID-19 lockdown rules then in place that forced the queen to sit alone wearing a black mask as she mourned the loss of her husband, who she called her rock.

Philip died on April 9 at age 99.

Tuesday’s service will feature the hymn “Guide Me, O Thou Great Redeemer,” fulfilling one of Philip’s wishes for his funeral that wasn’t carried out because of restrictions that banned singing.

Young people participating in programs run by the prince’s Duke of Edinburgh charity and youth cadet associations will line the steps of the abbey to greet guests for the service.

Britain’s royal family will attend, together with about 30 foreign royals, including Prince Albert of Monaco, Denmark’s Queen Margrethe, King Harald and Queen Sonja of Norway, and King Felipe VI and Queen Letizia of Spain.

Philip’s wider family and friends are also expected to attend, along with 500 representatives charities and other groups he supported.