On Sun, 27 Mar 2005 16:44:04 +0100, John Ray wrote:

From the above, is it legitimate for a passenger travelling from, say,
Aylesbury to Southend, to use LUL between Amersham and Upminster,

It certainly looks that way, though why anyone would want to do that is
a bit of a mystery. Presumably time to waste...

Break of journey is, I think, something of an issue.
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(Skye seen through mist and low cloud from Kyle of Lochalsh in 1999)