Britain's Queen Elizabeth
Britain's Queen Elizabeth smiles as she greets well-wishers on her 90th birthday during a walkabout in Windsor, west of London, April 21, 2016. PHOTO: REUTERS/STEFAN WERMUTH

Queen Elizabeth II enjoyed a pre-birthday lunch with close friend and fellow European royal Queen Sofia of Spain on Tuesday. She invited the Spanish royal to Windsor Castle for a private lunch.

The pair, distant relatives, reportedly sat down for a lavish meal at Windsor Castle, the queen's royal residence in Berkshire. Elizabeth carried out engagements in Windsor in the lead-up to her birthday. The 77-year-old Spanish royal took the opportunity to congratulate the queen and give her warmest wishes in person.

The intimate luncheon took place just two days before the queen’s milestone 90th birthday. Hello’s sister publication Hola reported that Elizabeth had in fact invited Sofia for the exclusive lunch. The duo share a very strong friendship and in spite of the queen having to address the issue of Gibraltar during her reign, they have remained friends over the years.

Elizabeth and Sofia are also distantly related as they descend from Queen Victoria. Sofia’s father was King Paul of Greece, the great grandson of Queen Victoria. Meanwhile, the British monarch is the great-great-granddaughter of Queen Victoria.

The queen carried out one official state visit to Spain in October 1988. At that time, Sofía was pictured warmly welcoming her counterpart with a kiss on both cheeks. Elizabeth had acknowledged the peaceful transition from dictatorship to democracy following General Franco’s death in 1975.

Earlier in 1986, Elizabeth and her husband Prince Philip welcomed Sofia and her husband King Juan Carlos to Windsor Castle. A state banquet was held in honor of the Spanish royals. It was the last state visit from Spain.

King Felipe and Queen Letizia of Spain were scheduled to carry out their first ever state visit to the U.K. in March. However, due to Spain’s political situation the trip was postponed.