First of all the firing order is 1, 3, 4, 2.  That is the order in which the cylinders fire (the plug wires in the distributor cap) when the engine is running. That makes the engine run smoother from a vibration standpoint. 

SO, you want to insure that the 'firing order' is correct.  As you look down onto the top of the distributor on your Little British Car the distributor will rotate counter clockwise.  The rotor needs to point to number 1 spark plug wire, then number 3 spark plug wire, then 4, then 2, then back to 1 again.

The cylinders are numbered, from the radiator,  at 1, 2,3,4 as you head toward the driver's compartment. The wires need to be in the order in the previous paragraph and connected to the appropriate cylinder.

The BEST way to adjust the valves is by starting at #1 (the front most cylinder).  Adjust those valves at 'top dead center' on the compression stroke.  That is,  there are TWO 'top dead center' positions on every stroke of the engine,  in every cylinder.  There is 'tdc' compression and 'tdc' exhaust.  If you adjust the valves on 'tdc' exhaust it won't work.  You MUST adjust them on 'tdc' compression.

To determine if you are at 'tdc' compression,  have the spark plugs out of the engine (I take them all out as it makes the engine easier to turn).  Turn the engine in the normal rotation direction (with the distributor shaft turning COUNTER clockwise as you look down on it from overhead, with the distributor cap off) until the piston comes to the top just after the intake valve closes (you'll have the valve cover off, of course).  I use a screwdriver sitting in the spark plug hole (don't let it get jammed as the piston comes up) and shortly after the intake valve closes (you'll be able to tell even if the valves aren't adjusted yet as they will be close enough) then the piston will come to 'tdc'.  Adjust both valves on the cylinder that is at 'tdc' compression.

Then turn the engine till the next cylinder is ready to be adjusted,  and so on.  THIS way you won't get confused as to which valve is to be adjusted 'next'.

Now.  As to the distributor position.  This is difficult but bear with me.  You'll get it.  What you need to do is put the distributor in the block so that the #1 spark plug position on the cap is lined up with the rotor contact tip when #1 cylinder is at 'tdc' compression.   See how it all has to work?  It's all in the 'timing' .   This will all occur just as the points open up and let the field in the coil collapse and the spark plug for #1 will fire.  

Now,  I hope that's clear.  As always,  if you have a question,  just ask.