A404
A404 Harrow Road, at junction with Chippenham Road on the left
Route information
Length	44.6 mi (71.8 km)
Major junctions
From	A40 (Westway) in Marylebone, London
Major intersections	A219 A406 A312 A410 A412 A413 A416 A355 A40 A308 A4 M25[1] M40[2] M4
To	A404(M) at Maidenhead
Location
Country	United Kingdom
Primary destinations	Wembley, Harrow, Northwood, Rickmansworth, Amersham, High Wycombe, Marlow
Road network
Roads in the United Kingdom Motorways A and B road zones
← A403 → A405

The A404 is a road in the United Kingdom that starts at Paddington in London and terminates near Maidenhead in Berkshire. It is 44.6 miles (71.8 km) long.

Route

The road initially follows a course through north-west London via Harlesden, Wembley, Harrow, Northwood and Rickmansworth. During this stage, it is known as Harrow Road. It crosses the M25 at Junction 18 at Chorleywood, crossing into Buckinghamshire and then continues towards Little Chalfont and Amersham.

Between Harrow and Amersham, the road closely follows the route of the London – Harrow-on-the-Hill – Aylesbury railway lines, The Chiltern Line from Marylebone, and runs near several stations along that line.

At Amersham Common, the road turns south-west and continues in that direction joining the Amersham by-pass (A413) for a short distance, and then proceeds towards High Wycombe. After passing through the town centre, and crossing the A40, it changes to a dual carriageway up the hill to the M40 Junction 4, and continues as a dual carriageway past Marlow and Bisham.

The road eventually becomes the A404(M) at Maidenhead Thicket. It then runs a short distance towards the M4 where the A404(M) finally terminates at Junction 8/9.^[3]

Harrow Road

The Harrow Road is an ancient route^[4] in North West London which runs from Paddington in a northwesterly direction towards Harrow. It is also the name given to the immediate surrounding area of Queens Park and Kensal Green, straddling the NW10, W10, W2 and W9 postcodes. With minor deviations in the 19th and 20th centuries, the route remains otherwise unaltered.

Harrow Road is also a ward of the City of Westminster. The population of this ward at the 2011 Census was 12,034.^[5]

History

By the 19th century, Harrow Road had become the main street in Paddington.^[6]

In the 20th century, many properties along Harrow Road were developed into high-rise social housing, though some 19th-century houses and commercial buildings north of the Paddington Basin were retained. These included Elgin Towers, constructed between 1966 and 1969, and demolished in 1994.^[6]

Cultural references

The 1950 film The Blue Lamp is set around Harrow Road and features it prominently.^[6]

In one version of the Bus Driver's Prayer, the line from The Lord's Prayer, "Hallowed be thy name" is replaced with "Harrow Road be thy name."^[7]

A404(M)

A404(M)
The northern end of the A404(M)
Route information
Maintained by National Highways
Length	2.4 mi (3.9 km)
Existed	1961–present
Major junctions
Northeast end	Maidenhead (west)
Major intersections	M4 motorway[8] A308(M) motorway[9]
Southwest end	M4 Junction 8/9
Location
Country	United Kingdom
Primary destinations	Maidenhead, (High Wycombe), (Henley), (Marlow)
Road network
Roads in the United Kingdom Motorways A and B road zones
← A329(M) → A627(M)

The A404(M) is a motorway in Berkshire, England and can be referred to as the Maidenhead and Marlow Bypass or M4/M40 link road. It joins the M4 with the A404 dual carriageway to High Wycombe, Marlow and the M40. It was originally known as the A423(M) until the A423 between Maidenhead and Oxford was reclassified as the A4130.

History

The road was originally opened in 1961,^[10] as part of the A4(M) Maidenhead Bypass^[11] which ran from the existing Junction 7, through a junction with the A308 and ending at a junction with the A4. In 1963, the Slough bypass was opened to Junction 7,^[10] and the A4(M) was renumbered M4, Junction 8 being with the A308 and Junction 9 with the A4.

The proposed route of the M4 was then changed to go south of Reading, instead of north of it.^[12] When the M4 was extended in 1971,^[10] a new junction was provided to connect with what would become a spur. As this new interchange was built too close to the existing Junction 8, this had to be closed. A new spur, the A308(M), was built to maintain access to the A308 and connected with the A404(M) and the M4 at the same grade separated roundabout. This new junction was numbered 8/9 so as not to confuse motorists and the interchange with the A4 became Junction 9A.^[13] The old M4 was renumbered A423(M)^[14] as it was a direct continuation of the A423 to Oxford.

Junctions

Information above gathered from Advanced Direction Signs April 2011