Most of the M1 is 'derestricted' a.k.a. the 'National speed limit' (indicated by a circular white sign with a diagonal black line through it). On a derestricted motorway, different speed limits will apply dependant on the vehicle being driven:
70mph
60mph
Some parts of the M1 are not derestricted and in these cases, the speed limit is well signed.
The first speed limit was passed in England in 1865, setting a limit of 10 miles per hour on trains operating in the country. The first speed limit on automobiles also comes from England; in 1896, a limit of 14 miles per hour was set on what was called at the time "light locomotives". Local governments were given discretion to lower the limit to 12 miles per hour in their towns.
The M1 Abrams tank has a top off road speed of 30 mph, and a top road speed of 42 mph.
103 miles if you take the M1
The distance from Edinburgh to Leeds is approximately 200 miles (322 kilometers) by road.
826 limit
speed limit is 34mph no speeding once a week
the posted speed limit
When another speed limit sign is reached that changes the limit from the previously posted one.
The speed limit is exactly that - the speed limit. While a reasonable excess of speed might be overlooked when overtaking another vehicle, there is no guarantee. You can be pulled over and cited for speeding, still.
The posted speed limit is the max speed.
In the UK the speed limit comes into force as soon as you pass the speed limit sign. As such the distance is zero as you should have slowed down to the posted speed limit before passing the sign.
The speed limit in built-up areas is 30mph, unless signs show otherwise.