Veterans are gathering to mark the 60th anniversary of D-Day at London's Imperial War Museum on Tuesday.
The D-Day landings claimed the lives of thousands
The Duke of Gloucester and Dambusters actor Richard Todd will join 100 veterans for the ceremony.
Field Marshal Montgomery's son, as well as former Conservative MP Sir Carol Mather, will also be involved in the commemoration.
The event comes as 10,000 British veterans prepare for the D-Day events in Normandy at the weekend.
Christopher Dowling, from the museum, said: "The weather is a bit of a problem at the moment and we're not too happy with the rain.
"But it is the most significant gathering of D-Day veterans in the UK. Some cannot go to the beaches so this is the next best thing.
"It is quite a historic reunion. We have worked closely with the Normandy Veterans Association and we are hoping it will be a day to remember."
Veterans from all over the country will arrive for the ceremony which begins with a performance by Portsmouth's Royal Marines Band.
Timetable of events 6 June
0900 Franco-American ceremony begins at the US cemetery in Colleville
1100 Bi-national service at Bayeux's British cemetery
1430 International march past on cliff top at Arromanches
1730 French national ceremony in Ouistream
1730 British veterans march in Arromanches
1820 Franco-German ceremony in Caen
All timings are local
The Duke of Gloucester is expected to follow and three speeches will be read before the ceremony ends.
Meanwhile, a convoy of 250 military vehicles have been loaded on to a ferry to sail to France in preparation for the 60th anniversary of the D-Day landings on 5-6 June.
A further 100 vehicles are expected to be shipped over to France over the next few days.