Two weeks ago, I was training up in the Peak District and since day one proved my trainee knew the roads in the area rather too well, on day two we headed out across Nottinghamshire and onto the very different roads between Gainsborough and the Lincolnshire Wolds, roads he admitted later actually did set a challenge.
As it happened, I was staying up in Lincolnshire for a couple of extra days after the training as Judy and I were headed to the brand-new television broadcast equipment museum which is situated at the old WW2 airbase at Hemswell Cliff.
As Waze took us on one of its less-obvious twisty turny routes through the countryside ("this route is one nano-second shorter" presumably), I was fairly astonished to turn a corner and discover myself head-to-head with a nodding donkey!
I was aware from my college studies that there are oil deposits in the UK, but my knowledge was limited to the development of the area around Kimmeridge in Dorset. First exploited as early as the 17th century, the shale rock was mined in sufficient quantity to support a mid-1800s tramway which linked to a small port. Most of the unrefined shale went to nearby Weymouth to be converted into varnish, grease, pitch and various other products, but some shale was shipped to Paris to power gas lighting.
But what was a nodding donkey - so synonymous with the US oil industry - doing in Lincolnshire?
It turns out that a oil-bearing geological feature called the 'Gainsborough trough' extends under the area near Hemswell Cliff, and it is itself part of the much larger 'East Midlands Oil Province' underlying parts of Lincolnshire, Nottinghamshire and northern Leicestershire.
Why hadn't I heard of it?
The answer may not be unconnected with the secretive origins of the oilfield.
It appears that exploration for oil and gas in the East Midlands was initiated during the First World War as a consequence of government concern about security of supplies as the U-boat war threatened oil tankers aiming to arrive in UK ports. Small quantities of oil were found at Hardstoft in Derbyshire, in 1919 but production never exceeded a few barrels per day and ceased in 1927.
Although some exploration took place between the wars, nothing of major significance was found but oil seepages into colliery workings continued to suggest that oil deposits were likely to be found in the East Midlands.
With tensions rising again, major exploration took place just before the Second World War commenced, and the UK's first commercial oil well was drilled at Eakring, between Newark and Ollerton.
The site, known as Dukes Wood, came on stream in 1939 with significant amounts of oil beginning to be pumped out, in what was to become a vital local oil source to supplement that being imported by ship.
The new onshore source of crude oil turned out to be of an astonishingly high quality, purer than anything being produced in Europe or the Middle East.
Refined via a new cracking procedure, the new '100 Octane' aviation fuel gave a significant boost to the performance of the RAF's Hurricanes and Spitfires, and arrived just in time for the RAF to engage the Luftwaffe in the Battle of Britain.
By 1942, with demand for oil rising further, reserves were running low and with the aid of oil industry professionals from the USA, over 100 further oilfields across the area were opened up right up to 1943.
Wells were soon producing an average of 700 barrels of oil per day as a national oil industry was being built up from scratch – an extraordinary undertaking.
To give you an idea of the importance to the war effort of this UK source of crude, more than 600,000 tonnes of oil was pumped out of Duke's Wood alone over the course of the war by no less than 170 nodding donkeys, whilst over 630,000 tons of oil was lost at sea as seventy nine tankers were sunk during the crucial months between September 1939 and February 1941.
Not surprisingly, this home-grown British oil industry was kept top-secret - even oil industry executives were astonished to hear about the wells from the minister when called to a meeting to discuss further exploitation in 1942. As far as I can determine, it wasn't announced publicly until 1944 when the threat from German bombing was all but over.
By 1965 fresh drilling had finished at Eakring although production continued there until 1989 on existing wells.
Post-war, BP discovered numerous small oilfields, but exploration virtually ceased in the late 1960s, only to be restarted after oil prices rose as a result of the 1973 Middle East War. This led to the discovery of the Welton Oilfield, around the village of the same name which is about five miles north of Lincoln. In the early 1990s, 1,000 tonnes of oil was being taken by train to the refinery at Immingham every second day.
Although BP pulled out in the 1980s, several smaller companies continue to exploit the resources.
The extraction facility I happened upon is (I believe) the East Glentworth field, discovered in March 1987, where production started in February 1993. Oil is taken by road tanker to Gainsborough. You can see an aerial view of the site here on Googlemaps:
As of last year, the onshore wells in the UK were producing something over 14,000 barrels per day - just under 2% of the total UK production.
Incidentally, five of the nodding donkeys at Duke's Wood have been restored. And ironically, the site is now in the middle of a nature reserve!