The Duchess of Sussex is scheduled to be with Harry in London for a bash celebrating the sporting achievements of wounded servicemen.
Meghan, 38, is believed to have left baby Archie behind as she flew in from Canada to complete her final round of official royal engagements.
Her husband was at Buckingham Palace and was reportedly holding talks with advisers.
His grandmother, the Queen, was also at the palace greeting official visitors.
Harry, 35, was said to have had a four-hour heart-to-heart with the Queen at the weekend but it was not clear if they met again.
Meghan and Harry were last in the UK together in January before the terms of their Megxit were agreed.
As well as tonight’s appearance at the Endeavour Fund Awards at Mansion House, the couple will be at Saturday’s Mountbatten Festival of Music at the Royal Albert Hall.
The Duchess will also face the Queen, Charles and Camilla and William and Kate for the first time since the split at Monday’s Commonwealth Day service at Westminster Abbey.
It will be the Sussexes’ final event as senior royals.
A spokesman for the couple refused to comment on their private schedule.