I do not see that this is still true, but I would be delighted to be proven wrong

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The Continental codeshare flights between MIA and LHR are numbers 8225 and 8226. Since early 2005 CO's lowest "Z" class fare rules on the LHR/MIA route typically stipulate: "APPLIES TO ANY FLIGHT EXCEPT CO 8219-8249", which excludes the codeshares.
For example, on the arbitrary date 1 February 2006, Expert Flyer shows these fares LHR - MIA ...
ZLAP VS Z Round-Trip 3804.00 (USD)
ZLSN3W CO Z Round-Trip 3914.00 (USD)
DLAP1 VS D Round-Trip 4922.00 (USD)
ZLAN3W CO Z Round-Trip 5032.00 (USD)
...and the ZLSN3W fare does not apply to the codeshare flights.
dennis
Originally posted by bostonbrit
FYI - you can often get to fly VS UC to MIA much cheaper on CO codeshare; you wont earn FC points, but that might not bother you...