Looks like a transition between LV overhead lines and LV cable. I suspect either insulation breakdown or a high resistance joint. Either could produce enough heat to ignite the bitumen or similar material in the joint. Since burnt or charred insulating materials are conductive, continued arcing will result. black smoke is also somewhat conductive.

Heat from the burning bitumen and from the arcing ignited the wooden pole. The arc would drop some voltage, unlike a dead short, and limit the current to less than that needed to promptly operate the substation fuses.

It needs an AFDD in the substation.

Well there is a man shouting "Turn the fuse box off," and shorting at the top of a mains distribution pole due to a breakdown of insulation.  Phase to phase shorting. 

AND, it's bin day AND that red car has lots of dead insects stuck to the windscreen. Plus the weather is nice.

It'll be cold spam sandwiches for tea then dear.

Z.

"Telegraph pole " ?

Now meet its international BIG BROTHERS!

https://www.youtube.com/watch?v=gOT8jx4jEzM

Z.

Anyone for surge protection?

And there's always someone stupid enough to walk under the overhead cables whilst they are on fire.

The village idiot.

Z.

I have seen a couple of pole fires.

The one I have described a few times on this forum over the years, the ground workers on a site decided to dig in the no-dig zone where the big cables run underground into Pershore and hit them with the big steel bucket on a 360 excavator.

I was at the front of the site and there was a ball of flames in the sky over a farm yard, I thought the farmer had blown himself up tinkering with machinery and ran over, I then realised the head of the H-pole was on fire where the overheads transitioned to under ground cables.

When I walked back to the site I said to the ground workers there had just been an electrical explosion and they said they knew as they had hit the underground cables, I said I had some bad news for them it had took the pole out as well around two hundred metres away.  

I just played that video on the TV, my wife is not impressed with the guy filming it on his mobile phone asking if anyone has phoned the emergency services.

After filming for four and half minutes of filming the guy holding the phone says someone should phone the DNO, sometimes I just despair.

One morning I phoned the fire brigade to report a car on fire on the motorway and the operator asked where the driver was, I said walking along the hard shoulder talking to someone on his mobile phone, the operator replied saying he wasn’t talk to them.