Glowing Ball of Light

This was prompted by a mention of a very similar object on Coast to Coast Am on December 4th 2015.
Around 7.30 pm on a warm, clear summer night in the late 1980s in a narrow street of small, Edwardian terraced houses in Harrow Road, Barking, Essex, England, I saw something very unusual.  Barking is just to the east of London.  This road is in a working class area with small two storey houses.
My wife and I were seeing some friends off and were standing outside the house. The roads in the area are fairly narrow, approx 50 feet from the front of one house to the front of the house opposite.  Each house has a small front garden with a path about 10 ft long with a gate onto a pavement (sidewalk) about 6 ft wide.
I was at the gate, facing the house and my wife and friends were facing the other way, and we were chatting to our friends.  As we did so there was strange hissing noise. I looked up and a glowing, bluey green sphere about 3-4 ft in diameter came over the roof of the house next door. It was a little higher than the chimneys.  I had a very clear view and there was no distinguishing marks, just sheer colour.  It was definitely not a balloon.  It glowed and the noise it made seemed electrical. it moved across the road, fairly quickly.
It was a bit of a comedy moment because as I pointed to where it was my wife and friends turned to see it, but it had moved.  I followed it with my eyes as it sped over the road and went over the rooftops opposite.  As the others turned around it had just disappeared over the roofs. They did hear it, however.  I ran across to the other side of the road and down a side street to see where it had gone but it was out of sight.
I think this was more likely to be some kind of unusual electrical phenomenon than a craft of any kind, although it was a "UFO".  The report on Coast to Coast of a similar thing being seen by a factory seemed identical.
The road:  
 https://www.google.co.uk/maps/place/47+harrow+road+barking/@51.5338305,0.0939844,3a,75y,180h,90t/data=!3m6!1e1!3m4!1s5JsESA7ClBOQrWC0IsHz9w!2e0!7i13312!8i6656!4m2!3m1!1s0x0:0x624b6d147f9e5c29!6m1!1e1 
It came from the left side across to the right, and the road I ran down to see where it had gone is just visible on the right.
Witness indicates that the date of the sighting is approximate.  PD