RootsChat.Com

Thanks Diana ... I had noted that death record, but haven't checked it yet.  Obviously it's worrying for my theory, as the decedent is exactly the right age, although the location, while near London, is not particularly close to his 1871 location (of course, under my theory he had moved to Southport, where his 2nd son was busy being born at this time!).

That's why I thought I would first lay out my theory to see whether anyone completely destroys it.  If not, then yes, I'll have to check out that death record.

Not researching my ancestors, but genealogical research, nonetheless.
Some years ago I was researching a murder which occurred in the mid 19th century close to my present day home, with a view to writing an article about it.
When I ran out of contemporary sources, I hit on the idea of trying to find descendants of the murder victim, to see if they could help me in my research, but as is often said, I found it was far more difficult trying to 'trace forward' than back.
I was at home one evening after spending the day making a fruitless search through news archive microfilm, when an old friend and former colleague called to see me at my home.
We had worked together as police constables, and he was now on the C.I.D., at the local police station.
We were both in the mood for a good moan.
I told him about my research, and of the difficulties I was experiencing with it.
When I had finished, he told me his problems.
He had arrested a team of travelling burglars, who had been targetting garages and car workshops everywhere between Cornwall and the Lake District, stealing tools, and valuable equipment. As a result of the arrest, he had recovered hundreds of thousands of pounds worth of stolen property, and he now had to try and reunite this property with its rightful owners.
This task would oblige him to spend the next few days in the office making telephone calls around the country, and he wasn’t looking forward to it. I murmured a few appropriately sympathetic words, and shortly afterwards, he left.
The following morning, I received a telephone call.
It was my friend, speaking from his office at the police station. ‘You will not believe this . . .’ he said  . . .
He went on to tell me he had arrived in his office a few minutes earlier, to start the telephone enquiries he had told me of the night before.
The first number he had dialled was that of a garage in Mawnan Smith, near Falmouth in Cornwall.
A young woman answered the phone.
He introduced himself, told her he was on the C.I.D., and gave the location of his police station.
‘That’s odd’, she replied, ‘one of my ancestors was murdered near there, years ago’.
My friend was talking to the great great grandniece of ‘my’ murder victim.
She was fascinated to hear of my research, and asked my friend to pass on her phone number to me.
She was able to put me in touch with other descendants of the murder victim, many of whom only lived a short walk from my home, and they were able to provide me with a great deal of information.
The article has still to be written!

If the Martin West who was at Hag Head in 1841 was born ~1765, this would be consistent with him being the grandson of the will-making Martin West, so perhaps he was the third life, as suggested in reply #2. Then upon his death the lease was transferred to Francis Shiers?