The couple are to tie the knot on May 19 at Windsor Castle and were keen to hold their wedding breakfast in stately home Frogmore House, Windsor Home Park - a mile away from the castle - but royal aides are said to have vetoed the choice.
A senior royal source said: "They would have loved Frogmore for the party, particularly Meghan, who has called it 'dreamy', but they have been told St George's Hall is far more practical."
St George's Hall is next to the chapel at Windsor Castle, but Frogmore was already said to be close to Meghan's heart because they had their engagement pictures taken there and she took Harry for a romantic picnic at the venue last summer.
It is also thought Queen Elizabeth would have "readily approved" of Frogmore being Harry, 33, and 36-year-old Meghan's reception venue. The source added to the Sunday Express newspaper: "One person who would have readily approved of their choice was the queen, for whom Frogmore is a very special place."
The queen would also have loved the family to see what had been done at Frogmore: the house has just been renovated by a group of friends as a 70th wedding anniversary gift to her and Philip.
The royal wedding is expected to bring a huge boost to the UK economy in May when fans flock from all over the world to get a glimpse of the action. Brand Finance's chief executive David Haigh recently said: "We think approximately £200 million will come from tourism, travel, and hotels."