Gripped as I seem to be by listmania, here is another:  of orchestras and ensembles I have seen perform live.   I omit chamber music groups, counting only ensembles large enough to need a conductor.

• Academy of St Martin in the Fields, London
• Aurora Orchestra, London
• Australia Ensemble
• Australian Brandenburg Orchestra
• Australian Chamber Orchestra
• Australian Youth Orchestra
• BBC Philharmonic, Manchester
• Boston Symphony Orchestra, Tanglewood
• Brandenburg Baroque Soloists, London
• Britten Sinfonia, London
• Canberra Symphony Orchestra
• Chicago Symphony Orchestra
• Birmingham Contemporary Music Group
• City of Birmingham Symphony Orchestra
• Ensemble 10:10, Liverpool
• Ensemble 11, Manchester
• European Brandenburg Ensemble
• Halle Orchestra, Manchester
• Hamburger Symphoniker
• Harare City Orchestra
• Hong Kong Philharmonic Orchestra
• Irving Symphony Orchestra
• Isabella a Capella
• Leipzig Gewandhaus Orchestra
• Lismore Regional Symphony Orchestra
• London Philharmonic
• London Sinfonietta
• London Symphony Orchestra
• Mahler Chamber Orchestra
• Manchester Camerata
• Medici Choir, London
• Melbourne Symphony Orchestra
• Merseyside Youth Orchestra
• Moscow Soloists String Chamber Ensemble
• Northern Sinfonia, Gateshead
• Orchestra of the Age of Enlightenment, London
• Orchestra Mozart, Bologna
• Orchestre Appassionato, Paris
• Orchestre National de France
• Orchestre Philharmonique de Nice
• Orchestre Revolutionnaire et Romantique, London
• Orquestra Gulbenkian, Lisbon
• Patonga Orchestra
• Queensland Conservatorium Chamber Orchestra
• Queensland Symphony Orchestra
• Royal Liverpool Philharmonic Orchestra
• RNCM Chamber Orchestra, Manchester
• Seoul Philharmonic Orchestra
• Siglo de Oro, London
• Silk Road Ensemble
• Solistes de Musique Ancienne, London
• Soweto Symphony Orchestra
• Sydney Symphony Orchestra
• Vienna Chamber Orchestra
• University of Liverpool Symphony Orchestra