Who was the first person to walk the coast of Britain

Oh his Facebook page, Craigs walk round Britain, Craig asks if John Merrill was really the first person to walk around the coast of the UK. It's an interesting question, and first we need some definitions:

1) The 'coast of the UK' is the mainland of England, Wales and Scotland.
2) The walk has to have stuck as close to the 'sea' as was practical.
3) It would have had to have visited the vast majority of settlements on the coast.

I've given this some thought in the past, and think that John probably was the first.

Firstly, you have the problem of time and resources to do such a tramp. Any such walk takes a practical minimum of nine months. Both time and money are needed, and the amount of people with both of these in past times were few.

Secondly you have legalities such as footpaths, which formally came into being in the 20th Century. Before then, large tracts of land would have been forbidden to walkers, limiting access.

Thirdly you need maps; again, OS maps really became commonly available in the 1900s. Without maps, such a walk would have been much more difficult, and would have very much depended on local knowledge.

Fourthly, any such tour would probably have been publicised, either by the writing of a book or other means. I've never been able to find any references to such a walk.

People will have travelled around Britain, visiting towns and keeping mainly to roads - for instance Pennant's tour of Scotland in 1769, or Johnson's tours of Scotland six years later. But none would have stuck 'to the coast' as it is now, or were on foot.

If anyone knows of any potential candidates, please let me know.