Classic/Antique Car Repair: XKE Ignition, combustion chambers, compression gauge

Question
Problem: After a 15 minute drive in my '67 2+2 XKE, at 60 mph the engine suddenly lost complete power, (no noticable/unusual sounds).  As I coasted to slower speeds, I dropped into third gear attempting to restart, the engine started only very briefly ~ backfired once/twice then lost power for good.
Once towed home,  the fuel pump checked out O.K. and I pulled a plug and confirmed spark at that plug. A quick check of the wiring looked O.K. and  nothing unusual with a visual check inside of the Distributor.   Now I can't get the engine to fire at all while attempting to start.   Thanks for any insights you might offer. My checks were  performed without any diagnostic instruments.  

Answer
Gary,
You need to start from scratch and do what mechanics do to check out an engine.
Get a compression gauge and check compression on all 6 cylinders. Be sure to hold the throttle open when testing. You should have 150 to 170 PSI on all cyclinders. You checked to see if you had spark but you need to know if it is at the correct time. A timing light will tell you this. There is a crude test without a light. Put a spark plug on any one of the wires and lay it up on the engine so you can watch it spark. Put your thumb over the plug hole that that wire and plug goes in. Have someone spin the starter. As that piston comes uo on compression it will cause the air in that cylinder to force your thumb up and make a "Pop" noise. The spark noise makes a "Click". If the timing is close to correct, the "Pop" noise will appear to be causing the spark. If the timing is off enough to make it not run, You will be able to see either a "Pop-Click" or a "Click-Pop".
Next is fuel, and to check fuel you need to establish weather fuel is getting to the combustion chambers. A quick easy method here is to remove the large plentum from over the air filter. This gives you access to the open throughts of the carbs. While someone spins the starter spray some spray in the throughts of WD-40 or some other combustable spray in the throughts.
These three tests will ID why and engine will not start.
let me know the results.
Howard