Haydn has considerable experience in working with massed choirs. He has conducted nine male choir festivals at the Royal Albert Hall (the '1000 Voices'), as well as choirs of between 300-800 voices in Brecon, Cardiff Castle (for the VJ Day Anniversary), the Wales Millennium Centre, St David's Hall, Sioux City Iowa, Toronto, Sydney Opera House and New York's Carnegie Hall.

As Musical Director working with the Welsh Rugby Union, Haydn has conducted bands, choirs and supporters at more than 65 international matches at Cardiff's Millennium Stadium over the past ten seasons. He has travelled to Murrayfield in Scotland, Stade de France in Paris and Newlands in Cape Town to conduct the singing and Welsh Anthem, as well as to Australia, New Zealand and South Africa with the British and Irish Lions Choir, where he led the singing before many of the Test Matches and entertained the supporters in 'The Lions Den'.

Haydn has also conducted the singing before many cup final games at Cardiff, Twickenham and Wembley, including the Heineken Cup, the EDF Cup, the Powergen Cup and the LDV Vans Trophy.

In 2008, he was honoured to appear at the FA Cup Final in Wembley, working with the Band of the Grenadier Guards, Lesley Garrett and Katherine Jenkins.

Haydn has been involved in two Rugby World Cup tournaments - in 1999, he was Assistant Musical Director in Cardiff, and in 2007 travelled to Paris to work with a French Choir and Band in the recording of five National Anthems for the tournament.

Future plans include the four Autumn Internationals with the Welsh Rugby Union at the Millennium Stadium, plus three Six Nations games in 2010. Haydn has also been appointed Musical Director for the Rugby League Challenge Cup Final at Wembley Stadium in August, his fifth appearance at this event.