(17 Jun 2024, 9:56 pm)Unber43 wrote I just wondered if anyone knows why the A690 and the A1 is both 50MPH in some stretch and not 70MPH?

The dual/triple A1 is only 50mph in the roadworks section and the built up Western Bypass section. 

Beyond that, I am pretty sure it is 70mph between the Bowes Incline and way down to a small section between Elksley (excluding roadworks). North of Morpeth, the limit varies.

The A690 has been renowned for a number of accidents and was a mix of 70mph and 50mph between the A19 and A1 (M) until relatively recently. 
The small stretch at the bottom of Houghton Cut has (or had) two conflicting speed limits. The road signs had a different limit to the markings on the road.
The 50mph limits were extended throughout the stretch and both Durham and Northumbria's finest like to park their speed camera vans up.