|From:||Leighton Buzzard (SP917234)|
|Length:||4.8 miles (7.7 km)|
|Old route now:||B5704|
|Route outline (key)|
Starting at a roundabout a quarter of a mile east of the A505's bridge over the Grand Union Canal, it first heads north-east along Grovebury Road, which serves a large number of light industrial premises. After a mile or so, the A4012 curves first left into Lake Street and then right to follow Leston Road into the town centre. At a small roundabout we turn right to enter Hockliffe Street, which becomes Hockliffe Road and leads us eastward out of town.
Just before leaving the built-up area the road crosses the narrow-gauge Leighton Buzzard Railway at an unguarded level crossing (with give-way signs rather than barriers). The southern end of this line is located on a former section of the A4012, while its northern end is at Stonehenge – though not the one on Salisbury Plain!) The A4012 continues eastward, zigzagging across the fields before reaching its terminus at traffic lights on the A5 at Hockliffe.
Originally the A4012 began on the A418 in the centre of Leighton Buzzard. In 2007, the A4146 was rerouted out of town with the building of the western bypass and the A4012 was extended south along part of the former B486 Boxmoor to Leighton road to meet the A505 southern bypass. More recently still, part of this extension was moved slightly west to serve an industrial estate rather than a residential area.
In 1922 – and for over 50 years afterwards – the A4012 ended at Hockliffe, as it now does once again, ever since the opening in 2017 of the Dunstable bypass. When, in the 1970s, the A50 which originally started more-or-less opposite was cut back to begin at Northampton, the A4012 was extended along part of the A50's old route, crossing the A5 at a staggered junction between adjacent sets of traffic lights before passing to the west of Woburn Abbey to reach the village of Woburn. The A50 continued straight from here along what is now the A5130 but the A4012 TOTSOed right along the former A418, continuing to skirt Woburn Park. The 1970s extension ended on the A507 at Husborne Crawley but with that road's rerouting as part of the upgrade scheme for M1 junction 13 in the 2000s, the A4012 continued straight (along a formerly unclassified road) to go under the M1 to end at a roundabout on the new A507 close to Ridgmont Station.