And all for the want of a Horseshoe Nail

Not in my case; but a little spring that had become aged.

Indicated with a yellow arrow

The villain of the day.  I had remarked to my passenger neighbour 

"I found I had £13 + change in my purse yesterday" when we parked outside of the Co-op shop in Old Street.

Hubris as the Ancient Greeks would have put it.
When we came out I had the normal contortionist problem getting my feet inside. (Oh how I wish I had been born to a frame of 5'9 feet.) Shoving the gear lever into reverse I started to back out.
Something was odd with the gear stick. It was loose and wobbled all over. I managed to manually shove the rebel back and then I realised that I had not got a screwdriver in the car. Over the road was proper Job. £3.99 for a screwdriver set with various bits.
Took off the rubber cover and found that the stick would just remove completely from the top of the box. 
First Re-action "Oh my God; I had the same thing happen in Bristol when I had the Rialto."
This was different though. To fix it required a new spring. The old one over the years had weakened and on my rather robust tug to lift the stick into reverse had let the fitting go.
Glory Be, I could get home without calling the Britannia Rescue because although sloppy I could access the forward gears.
Back home I went. An Email to Joe Mason up in Cradley Worcs. 
Meantime I was marooned at home. It arrived on Tuesday and I tried but didn't have three hands. Wednesday a neighbour helped me as I held the spring fitting down that controlled the stick he manipulated the new spring into place.
Victory except that I had looked for jubilee clips because at the worst I had an idea to use one on the old spring. £5.99p at Proper Job for a set of about 30. I only wanted one but there you are.
Now  :--- 
Was it Hubris that caused the whole outcome?
Or was it just old age of the original?.