The following thoughts are generic to carbureted automobiles, not
specifically to
the series 2 Jaguar.

I'm a dummy on series 2, but doesn't it have 2 fuel tanks? Or is that
just series 3?
Is the fuel pump mechanical or electrical? Is the carburetor choke working?

How do you know fuel is not getting to the plugs... are you looking down
the
carburetor throat when the starter is running? If you pull back quickly
on the throttle
linkage, (ie, jazz the throttle) even without the starter running, can
you see that the
accelerator pump is NOT shooting fuel into the carb throat? It should be.

It may still be possible that there's water in the system... I don't
think water is miscible
in gasoline (and vice versa)... since water is heavier than gasoline,
perhaps it
displaced the gasoline in the fuel pump and feed line from the tank
while it sat
so long. You didn't say HOW you rid the system of the water when you
discovered it.
If you didn't drain the system at it's lowest point(s) there may still
be water present.
Or, you could disconnect the fuel line at the carb and use the fuel pump
to pump
a few quarts of "fuel" into a container to clear water out of the line.

And, if you disconnect the fuel line at the carburetor and run the fuel
pump, you can
collect some fuel from the line into a glass container... then pour some
clean gasoline
from another source into the glass container and let it sit a few hours,
and perhaps you'll
be able to see whether the gas separates from the fuel (I haven't done
this, but it may
be possible to see the separate layers when they stratify... you could
test the theory by
trying this first with some tap water and some uncontaminated gasoline
from another car)

If you haven't already, you may need to block the line at the tank,
disconnect it from the
carb, and blow the line out with air, wouldn't hurt to remove the carb
to tip & drain it, also.
I'm not familiar with your carb, but usually there is an air vent tube
(about 1/4 inch diameter)
sticking up from the carb... you can pour gasoline down that tube to
pre-fill the float chambers
after you re-install the carb, before you start the car, which may give
enough running time
to remove the air from the tank-to-carb line and allow normal fuel flow.
 BTW, if you
aren't seeing fuel being squirted into the carb throat when you quickly
rotate the throttle
linkage (as I mentioned above), then try this "fuel down the vent tube"
approach and try
jazzing the throttle again to check for squirts of fuel.

Alternatively, the engine can tolerate water along with fuel once it is
started, as long as
it gets more fuel than water, so perhaps another approach might be to
remove the air cleaner,
start the car using engine starting fluid, and continue to spray
starting fluid down the air horn
to keep the engine running for at least a few minutes... eg, as long as
it takes to use
up any fluid in the tank-to-carb line.

Beyond that I suppose it's possible the water corroded something inside
the carburetor
that's causing, for instance, the float needles to stick, but that seems
unlikely, especially
since the water wouldn't have made it to the carb until you started it
after the 3 months,
so water hasn't been in the carb very long.

Good luck.

Thanks for your help Jo.

Tony