The three Scottish rivers:
(1) rises on the Northern flanks of Ben Avon in the Cairngorms and flows roughly Northwards to join the Spey near Bridge of Avon.
(2) rises on the moors between Cumbernauld and Longriggend, before flowing past Slamannan, Avonbridge and Linlithgow to enter the Firth of Forth between Bo'ness and Grangemouth.
(3) rises on the moors between Darvel and Muirkirk in Ayrshire, before flowing in an East/North-East direction into Lanarkshire past Drumclog, Strathaven, Stonehouse and Larkhall to enter the Clyde just South of Hamilton.
Meanwhile, South of the border:
(4) The 'Shakespeare' Avon - already mentioned.
(5) The Wiltshire/Hampshire Avon - already mentioned.
(6) The Bristol Avon - rising on the Northern edge of Salisbury Plain and flowing past Chippenham, Melksham, Bradford-on-Avon, Bath and Bristol, before flowing into the Severn Estuary/Bristol Channel at Avonmouth.
(7) The Devon Avon - rising on the Southern flank of Dartmoor, West of Buckfastleigh, and flowing roughly Southwards past South Brent, Avonwick, Kingsbridge and entering the English Channel at Salcombe.
(8) Where is it?....Can't find it!
Then, crossing the other border:
(9) The Glamorgan Avon/Afan, which rises in the Mountains between Aberdare and Neath, flowing through Glyncorrwg, Cymmer Afan and entering the sea at Aberavon/Aberafan just North of Port Talbot.