Intermittent non-starting

On Friday, having driven about 20 miles, including a brief stretch on the M11, I parked up and turned off the ignition. Five minutes later when I tried to start up again, the ignition wouldn't turn over. Dash lights were on and headlights working. Click from engine, but not even a halfhearted attempt to turn over. The next morning, I returned to the van with nothing more in mind than checking I did in fact still have fuel before calling out the AA, I gave it a try and it started first time. Started again today and was fine for the drive back to London.
Any suggestions what might be the cause of this kind of intermittent fault? I have seen PFM's post and will have a look at the connectors, but wondered if there any other known problems that manifest themselves in this way?

dodgy starter motor keep a rubber mallet in the van and give the starter motor a good whack and try again I had a motor go like that on my car.

Yep-- sounds like the classic symptom of a faulty solenoid on the starter motor.
It usually happens more and more frequently --then finally dies.

I fully agree.

Also I have a reconditioned starter motor spare

Today I ran the van on LPG for the first time and the length of time before the starter decided to function again was longer than before. Does the engine run hotter on LPG (due to revving more)? Could temperature be a factor?

I think there is more heat on LPG but I'm not sure but yes heat is the problem I think the plain bearings go dry and tihten up.

I'm nodding like I know what the plain bearings are

I think that they do run hotter on LPG. I have noticed that my engine
is running warmer in this weather and I switch back to petrol and the temperature gauge drops.

I'd say your time length game is just luck, maybe even weather and astronomy dependant!

Engine running temperature is mostly determined by the thermostat, doesn't matter what fuel goes in it. Maybe the exhaust manifold would have a different temperature on LPG or petrol, but the starter is on the other side of the engine than the exhaust manifold.

Don't waste too much though on it, just chuck a starter motor on it.

HighlyJetted wrote: but the starter is on the other side of the engine than the exhaust manifold.

The exhaust may be on the other side of the box and engine temp controlled by the stat but a hotter exhaust will heat the box by a small anound and heat transfer does happen so I wouldn't rule it out but it wont have as much affect as a starter wrapped by the exhaust and block.

A plain bearing is a shaft with a bronze bearing to run in with a little grease where as a most people think of a roller bearing with ball bearings inside.