English counties in which we have, together, walked at least 8 miles, are listed below and linked to the associated page. Map of the counties here.
It is extraordinary to realise that there is not a single European State that is as old as, say, Hampshire. We do walk in ancient boundaries ....
More information about counties, on wikipedia, here and from The Historic Counties Trust, including a UK map. Read about why we are so confused about counties, administrative and historic, from County-Wise who also provide a map and county details.
In covering the 39 English counties and the 13 Welsh we hope to show how easy it is to find good walks and places of interest everywhere in England, while enjoying good company. It really isn't a box ticking exercise, it's a way to encourage us to get out there and see the whole country, and we hope to continue even after we've bagged them all.

Wales
With all English counties covered, The Four Walking Boys have now also completed Wales. There is an extraordinary variety of landscape and history in Wales and we are delighted to have seen a glimpse of it.

Scotland
Also, Duncan achieved his target of walking in all 86 traditional UK mainland counties (there are still 6 in Northern Ireland = 92) - hence the links on the list of 34 Scottish counties (below).
Walking Boys' total 52, Duncan's UK total : 86, thankfully his knees held out ....

England

Wales

Ancient Counties of Wales (1891)
1. Carmarthenshire, 2. Glamorganshire, 3. Montgomeryshire, 4. Brecknockshire, 5. Cardiganshire, 6. Merionethshire. 7. Denbighshire, 8. Pembrokeshire, 9. Caernarvonshire, 10. Monmouthshire, 11. Radnorshire, 12. Anglesey, 13. Flintshire

Scotland

Ancient Counties of Scotland 1890 to 1975

1. Caithness, 2. Sutherland, 3. Ross-shire (Ross & Cromarty from 1890). 4. Inverness-shire, 5. Nairnshire, 6. Morayshire, (also known as Elginshire until 1918), 7. Banffshire, 8. Aberdeenshire, 9. Kincardineshire, 10. Forfarshire (Angus from 1928), 11. Perthshire, 12. Argyllshire, 13. Buteshire, 14. Ayrshire, 15. Renfrewshire, 16. Dunbartonshire, 17. Stirlingshire, 18. Clackmannanshire, 19. Kinross-shire, 20. Fife, 21. East Lothian, (Haddingtonshire until 1921), 22. Midlothian (County of Edinburgh until 1890), 23. Linlithgowshire (West Lothian after 1924), 24. Lanarkshire, 25. Peebleshire, 26. Selkirkshire, 27. Berwickshire, 28. Roxburghshire, 29. Dumfriesshire, 30. Kirkcudbrightshire, 31. Wigtownshire, 32. Zetland (Shetland), 33. Orkney 34 Cromartyshire (Ross & Cromarty from 1890)

Northern Ireland

Ancient Counties of Northern Ireland

Antrim, Armagh, Down, Fermanagh, Derry / Londonderry, Tyrone (6)
An excellent source of walks in the six counties is WalksNI.com

Key facts about the 92 historic counties of the UK are here and more information is at The Historic Counties Trust. Wikipedia also has definitive lists of ancient counties.

Here is the full list of 92 UK counties in A-Z order following the rules laid down by The Historic Counties Standard.

Aberdeenshire, Anglesey, Angus, Antrim, Argyllshire, Armagh, Ayrshire, Banffshire, Bedfordshire, Berkshire, Berwickshire, Brecknockshire, Buckinghamshire, Buteshire, Caernarfonshire, Caithness, Cambridgeshire, Cardiganshire,, Carmarthenshire, Cheshire, Clackmannanshire, Cornwall, Cromartyshire, Cumberland, Denbighshire, Derbyshire, Devon, Dorset, Down, Dumfriesshire, Dunbartonshire, Durham, East Lothian, Essex, Fermanagh, Fife, Flintshire, Glamorganshire, Gloucestershire, Hampshire, Herefordshire, Hertfordshire, Huntingdonshire, Inverness-shire, Kent, Kincardineshire, Kinross-shire, Kirkcudbrightshire, Lanarkshire, Lancashire, Leicestershire, Lincolnshire, Londonderry, Merionethshire, Middlesex, Midlothian, Monmouthshire,, Montgomeryshire, Morayshire, Nairnshire, Norfolk, Northamptonshire, Northumberland, Nottinghamshire, Orkney, Oxfordshire, Peeblesshire, Pembrokeshire, Perthshire, Radnorshire, Renfrewshire, Ross-shire, Roxburghshire, Rutland, Selkirkshire, Shetland, Shropshire, Somerset, Staffordshire, Stirlingshire, Suffolk, Surrey, Sussex, Sutherland, Tyrone, Warwickshire, West Lothian, Westmorland, Wigtownshire, Wiltshire, Worcestershire, Yorkshire.

See also the full text of Daniel Defoe's "Tour through the whole Island of Great Britain" (1724-1727)