Sides beginning with letter "A"
Sides without Web sites are now listed. Colours: Open, Ring, Federation. Carnival Morris Troups are marked in pink!
Updated: 
I cannot guarantee that these are all the A's, but they have been checked! Only B-W to go ...
Abbots Bromley (&) Horn Dance, Staffordshire
Abingdon Traditional Morris Dancers, Abingdon, Oxfordshire
Abingdon Morris Dancers (Mr Hemmings Traditional), Abingdon, Oxfordshire
Abram Morris Dancers, Wigan, Lancashire
Acorn Morris
Adderbury Morris
The Adderbury Village Morris Men Picture at top of page
Adlington Morris Men
A-Jays Morris Dancers, Bolton, Lancs.
Albion Morris
Aldbury Morris Men, Aldbury, Tring, Hertfordshire
Alford Morris, Alford, Lincolnshire
Alive and Kicking, Exeter, Devon
Alive & Kicking, Maldon
All Fools Morris, near Conwy, WALES, UK
Allington Morris, Lincolnshire
Alton Morris, Alton, Hampshire
Alvechurch Morris, Alvechurch, WORCESTERSHIRE
Amb Tro Mummers {See Boggarts Breakfast, this seems to be their calendar}, Sheffield, SOUTH YORKSHIRE
Amersham Garland Dancers
Amoundless Ladies, Preston, Lancashire
Ancient Men, Oxford, Oxfordshire
Annie's Fantasies, Colchester, Essex
Anker Morris Men, Nuneaton, Warwickshire
Anonymous Morris, Poole, Dorset
Anstey Morrismen [Everard's Brewery], Anstey, Leicestershire
Anstey Royale Chalfont (Ladies NW), Anstey, Leicestershire
De Antwerpse Zwaarddans - Sword Dancers from Anvers, Antwerp. Closest I can get is Folkroddels, main Belgium Folk site
Appleyard, Malvern, Worcs. Needs checking for existence!
Argarmeles Clog Morris team, Formby. (connection: Bothy Folk Club, Southport)
Armaleggan, Oxford
Arrowhead, Fareham, Hants. Now Belles and Arrows Morris
Armitage Mummers, via Master Mummers. {See Litchfield MM on Facebook} Armitage, Staffordshire
Ashdown Forrest Morris Men, Sussex
Ashdown Mummers, The World Famous, Ashdown Forest, East Sussex
Ashley's Rise Junior Morris See also The Great Caper
Ashwell Mummers, Hertfordshire
Aynho Apricots, Brackley, Northamptonshire