There are four houses, these houses and their colours are:-
Lourdes - Blue
Lourdes in France is where Mary appeared to St. Bernadette.
Fatima - Yellow
Fatima is a place where Three Secrets were given to three children as prophecies from the Blessed Virgin Mary.
Walsingham - Green
Walsingham is a village famed for its religious shrines in honour of Our Lady. It is a major pilgrimage centre.
Carmel - Red
The Camelites sometimes refer to Mary as Our Lady of Mount Carmel in honour of the legend and celebrate her on 16th July.