Morning dress (or 'formal day dress') is the traditional dress for weddings and formal daytime events in the presence of The Queen, such as Royal Ascot and Trooping the Colour.
The morning coat has curved front edges sloping back at the sides into long tails. It is single-breasted with one button, and usually has peaked lapels. Black or grey morning coats are nowadays considered equally acceptable.
Although grey is the traditional colour for a waistcoat under a black morning coat, patterned or coloured waistcoats are also acceptable. Brocade is a common choice, although silk might be more comfortable at a hot reception. Single-breasted waistcoats should be worn with the bottom button undone. If the waistcoat is double-breasted, all buttons should be fastened. Avoid backless waistcoats as you will not be able remove your morning coat.
Trousers should be grey with a grey morning coat, or grey and black striped (or grey houndstooth) with a black coat. One pleat down the centre of each leg is traditional and flattering for slim men. Flat fronted trousers are therefore more suited to heavier men.
Morning dress should be worn with a plain shirt (traditionally white with a stiff turned down detachable collar), although cream, pale blue or pink is equally acceptable. It should be double-cuffed, with appropriate cufflinks. The tie or cravat is traditionally of heavy woven silk. Black or silver is traditional, but non-garish pastels are frequently worn.
Formal black shoes should be laced-up and highly polished, worn with black socks. Grey felt top hats are easier to come by than black silk ones. These are largely optional at weddings (except for the groom and his men). For the Royal Enclosure at Ascot they are obligatory and must be worn at all times.
Top Tip: at weddings, top hats should be be carried rather than worn inside the church or in official photographs.