|East end:||A1 Black Cat Roundabout near St Neots|
| A1 road
|West end:||A43 near Brackley|
The A421 is an important road for east/west journeys across south central England. Together with the A428, the A43 and A34, it forms the route from Cambridge through Milton Keynes to Oxford. The section between the A1 near St Neots and the A5 in Milton Keynes is a national primary route.
The road begins at the A1, just south of St Neots (and the junction with the A428 from Cambridge), at the Black Cat Roundabout. The road bypasses both Great Barford1 and Bedford to the south to reach the M1 at junction 13. From there, it swings up through the southern part of Milton Keynes, doubling as the local grid road H8 Standing Way. During this time it crosses the A5 (and connects to it via a short spur which is part of the V6 Grafton Street). Continuing westwards, it forms the Buckingham by-pass before joining the A43 (Northampton — Oxford) on the outskirts of Brackley.
The section from the A1 to the M1 is dual carriageway and fully grade-separated. There is a short section of single carriageway from the new flyover (beside Junction 13) to the south-eastern outskirts of Milton Keynes, where dual carriageway running resumes and continues as far as the southwestern outskirts. From here to the A43, the route is single carriageway, with the exception of the bypass around Tingewick.
In conjunction with the M1 widening schemes and the widening of the A421 between M1 Junction 13 and Bedford that is already finished, proposals have been put forward to also widen the A421 between the M1 junction 13 bedforshire and the Kingston roundabout in Milton Keynes.2 Exhibitions were held in June 2005 which rejected proposals to re-route the road in favour of widening the current road. The scheme was given in 2005 an estimated total cost of £33 million.3 The scheme is currently seeking funding through government bodies and other sources.4
The A421 Tingewick bypass, near Bicester has a minor claim to fame as the location of the then fastest speeding incident ever recorded5 by British police, in March 2003. Andrew Osborne, 31, of Leamington Spa, was filmed by a mobile speed camera while travelling at 157 miles per hour (253 km/h) on a motorcycle. His friend Neil Bolger, 30, of Gaydon, was clocked at 148 miles per hour (238 km/h). Both were convicted of dangerous driving, imprisoned for 28 days and banned from driving for two years (with a compulsory re-test).
Blind Martine Brooks drove along the newly constructed A421 Great Barford Bypass (From the A1 Black Cat Roundabout to Bedford) and back to raise money for charity.6 The drive took place two days before the official road opening, and she was accompanied by Frank Branston (Mayor of Bedford), Steve Clarke (Teacher and Navigator), and Denise Hubbard (Driving Instructor and Car Owner).
She reached a speed of 65 miles per hour (105 km/h) before doing a flawless three point turn, and returning to the A1.
- The Great Barford (A421) Driving Challenge
- Highways Agency response to a query about widening the Berry Farm Underpass to allow for the canal (made under the 'Freedom of Information Act')
- The Great Barford bypass opened on 24 August 2006.
- "A421 Miton Keynes to M1". South East England Regional Assembly. Retrieved 2009-07-22.
- "Bedfordshire Local Transport Plan 2006/07 - 2010/11 - Major projects". Bedfordshire County Council. Retrieved 2008-12-09.
- "A421 Improvements M1(J13) to Milton Keynes". Bedfordshire County Council. Archived from the original on 14 November 2008. Retrieved 2008-12-09.dead link
- http://www.thamesvalley.police.uk/news_info/planning/pdf/ar2003-04.pdf Thames Valley Police Annual Report 2003/04
- "A421 Great Barford Bypass Third Newsletter - August 2006". Highways Agency. Retrieved 2008-12-29.