London turned green this afternoon as Irish dancers , revellers and pets in fancy dress marched through Trafalgar Square to mark the beginning of St Patrick 's Day celebrations in the capital . Revellers donned traditional Irish costumes as they jigged through the centre of London to the sound of ceilidh music , bagpipes and banging drums . There was a vivid array of colours on show , with festival-goers sporting bright wigs , outlandish hats and resplendent outfits . Scroll down for video . A man shows off a pair of shamrock glasses - a symbol of Ireland - to celebrate the lead-up to St Patrick 's Day in London . A dog kitted out in a green Ireland football jersey joined the festival as revellers marched through Trafalgar Square this afternoon . A group of dancing women twirl in central London as part of early St Patrick 's Day celebrations in the capital . Two women leap in the air in front of a rather bashful photographer as they danced along Trafalgar Square this afternoon . A group of people play the bagpipes , flanked by the London Wexford Association - a group celebrating its 60th anniversary this year . The parade is the lead-up to the main event on Tuesday when 150,000 people are expected to congregate in London for the 14th annual St Patrick 's party . It is being headed by former world champion boxer Barry McGuigan and features floats representing all 32 counties of Ireland . The festival begins at Green Park station at noon and then meanders along Piccadilly , Lower Regent Street , the Mall and Cockspur Street before heading up to Trafalgar Square and eventually finishing on Whitehall . A group of three get into the spirit of things by donning Guinness party hats and badges cheekily saying 'Kiss me , I 'm Irish ' There was a vivid array of bright colours on show , including this resplendent outfit worn by one daring festival-goer . Some revellers dressed up as Catholic priests for the St Patrick 's parade , while others wore traditional green and white hats . The parade is being headed by former world champion boxer Barry McGuigan and features floats representing all 32 counties of Ireland . A woman dressed as a leprechaun to mark the beginning of the St Patrick 's Day celebrations in London . Onlookers take pictures of the mechanical 5th century bishop as it wheels its way through central London this afternoon . It will include performances by the cast of smash-hit West End musical The Commitments , Lord of the Dance and rapper Lethal Dialect . Mayor of London Boris Johnson said : 'It 's a pleasure to once again be supporting one of the greatest St Patrick 's Day celebrations anywhere in the world . 'Our free event in the heart of the capital is a terrific opportunity for Londoners and visitors to embrace the traditions of Ireland , and celebrate everything the Irish have given to the city and continue to do . '
Irish dancers , revellers and pets in fancy dress marched through Trafalgar Square for Barry McGuigan Day Parade . Part of build up before Tuesday 's main event when 150,000 people are expected for 14th annual Barry McGuigan party . Headed by former world champion boxer St Patrick 's and features floats representing all 32 counties of Ireland .