Due to other business the Mog was in the garage for some two weeks.
This morning I inserted the key into the starting lock, turned the key till the speedometer had completed the starting dancing and turned further to start the engine - and nothing (not even a slight clicking sound) happened. Yellow engine control light on, red battery charging light on, headlights did work, the valve presetting sound was there, but NOTHING from the starter unit.

The battery had no problems so far, but because of the two week brake I was not sure so got the car onto the loading unit and after 30 minutes she started like no problems ever before.

We had a splendid drive for some 200km with one stop for several hours and on the way home another stop at a supermarket.
There the CAR DID NOT START! I called a car emergency service who promised to arrive within 45 minutes. To get everything ready I opened the fuse box and checked the fuses. Everything OK.
Than I turned the key to check the alarm-lights and she started instantly.

I drove the car to my home garage, got our stuff out and checked starting procedure: lights and everything else OK, but not even a click from the starter....

Has anyone got an idea which bug is biting the starter?
Maybe only the battery to be changed (seems to be still strong, but who knows and I had something similar on a Landrover last year) or should I search for something else?

Try the earth from the car to the chassis. for you it will be on the drivers side from the gearbox to below the chassis below the windscreen washer bottle if it is like my Roadster.
I had a similar issue and was about to change the starter but tested this & on clean up it works.

Hannes, my first thought leads to the sensor ring. On my former Roadster Series 2 from 2008 it was loose and it was often the culprit if the car did not start. Then I had to readjust it. At the 4/4 it is usually a good fixed inductive ring around the key lock.
Here Dave writes about his one re the Plus 4. Can you see if the blinking light of the immobilizer will turn out, it is under the dash at the very end in the middle above the foot department.

http://www.talkmorgan.com/ubbthreads.php/topics/539514/1

Thank you both for your comments. i will check both options

I had in mind the sensor of the starter key might be a possible reason for the problem and had both keys with me.
Both keys provided same results.

I had the same problem on my Plus 4. The problem was that the 12 volt was not being applied to the starter motor solenoid. The solution was to locate the connector between the internal harness and the engine harness. Break it open, use some contact cleaner, and plug back together. In my case the connector was on the extreme right side, under the dash. I did take the precaution to treat all connectors to the same treatment. Some months later my Plus 8 developed a similar fault, again a harness connector.

I had the same problem 4 weeks ago, for 3 times at my 2010 Roadster S3 (with start button, not sure if this makes a difference). The former owner reported it in 2 occasions. Full battery, all seems ok, all control lights on, but no click / start.
Problem was that the starter was "hanging, had not gone back to zero position. It helped in all situations to knock against the starter with a hammer or similar (under right bonnet, cylinder with red mark for plus / jump-start), not strongly, just to support the mechanism to go in original position.
This happened when I was driving for a longer time in very warm conditions. Since then not a problem any more...

I had the same problem 36 years ago with my first VW Golf series 2, where a hammer was my best friend… :-)

PS: I forgot that the starter seems to reset when cooling down, by itself. This could have happened in your case. When still warm, soft use of hammer

No "hanging of the starter" by definition.
I even pushed the car to get a rolling start (did not work)
It does seem to be a contact or immobilizer issue.

I think Marcel was describing a sticking starter solenoid, the one that sits on top of starter motor. The armature can corrode and stick in casing, hence a tap with (soft) hammer freeing it. This usually manifests as loud click and no starting action though.

I would also go with immobiliser issue.

It sounds like the same problem mine has. According to the dealer it is an immobiliser issue.
They sent the immobiliser and all keys back to Morgan to be replaced or repaired.

The trick in the thread that Heinz mentioned did work.
I could switch off the immobil by holding the key against the lock untill the immobiliser light went off.
They I could put it in and start the car.