On Tue, 02 Jan 2007 20:14:32 GMT, Peter Lawrence wrote:

It seems from NRE
(http://www.nationalrail.co.uk/times_...lFares.html#01)
that London Thameslink is abolished; one must ask for (and will get a
tocket to) the individual station one wants but the fare will be that
ffor travel to National Rail Zone 1

I don't think it's entirely clear that London Thameslink is abolished.
For a start, fares from stations between Radlett and Bedford to London
Thameslink seem to be outside the scope of the document. And I take
what it says about fares being issued to individual stations to mean
that they're retrofitting the zonal structure to the existing fares
system (in other words, keeping the point-to-point fares but adjusting
all the prices of those fares to what they would be if they were
zonal), rather than that they're eradicating all existing fare
destinations that don't consist of a single named station. So I'd
expect London Thameslink, having existed as a destination before the
change, to survive.

Nothing is said about whether
tickets are then valid to or from other stations in that zone

Yes it does (if, as you're assuming, they're issued to a named
station), and the answer is no. Example:

"SINGLE: Valid at any time for travel between any two named National
Rail stations in the London Fare Zones area."

PS. NRE seems to be telling me that NR tickets are valid from
Farringdon to Moorgate on NR trains but not LU trains. If true, it
strikes me as unenforceable.

Unless something has changed, they are, provided they're not marked
"FCC Only" or "Not Underground" or similar.