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|---|---|---|---|---|
 The A421 looking towards Buckingham from Maywynn Farm. | ||||
| Route information | ||||
| Length | 44.4 mi (71.5 km) | |||
| Major junctions | ||||
| East end | A1 Black Cat Roundabout near St Neots | |||
 A1 A43 | ||||
| West end | A43 near Brackley | |||
| Location | ||||
| Country | United Kingdom | |||
| Primary destinations | Bedford Milton Keynes | |||
| Road network | ||||
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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.