A423(M) Maidenhead Bypass

Where was it?

West of Maidenhead, Berkshire.

Can you show me that on a map?


What makes this a pathetic motorway?

This is one of those "Lost" motorways, but this is one with an odd history.

Odd? In what manner?

Well, it started life as part of the A4(M), then became part of the M4, then became the A423(M) in 1971, and then became the A404(M) in about 1990.

That's a lot of numbers.

It certainly is. I think that that's pretty much the "largest number of different motorway numbers along a single stretch of road" record.

So, why did it change?

Well, I'll let Matt Smith answer that:

"The A423, until about 1990, ran from Maidenhead to Oxford, then up to Banbury and then Coventry. Then they opened the M40 north of Oxford, and they decided that traffic from Banbury to Oxford should use the M40 and A34, so they renumbered the Oxford stretch (A4260). They also renumbered the Oxford-Maidenhead stretch as well, which became part of the A4074 and A4130. (Only the Banbury-Coventry stretch is still the A423, along with a small stretch of the Oxford Ring Road which for some reason they didn't re-number when the rest of the A423 disappeared.)

So that left the A423(M) without the road it led into, because anyone going from Maidenhead to Oxford would be expected to go via High Wycombe. So it became the A404(M).

Have you got a map?

Yes, this Ordnance Survey sheet from 1974 shows things nicely.

Can I comment on this motorway?

Of course! Contact me and I'll put them here!

Have any other visitors commented?

Peter Harris starts things:

"The A423(M) became A404(M) in 1992 to coincide with the opening of a short bit of dual carriageway linking the Thicket Roundabout (A4) with the end of the existing A404 dual carriageway at Burchetts Green. This new section followed the route of the erstwhile A423.

The A404 used to continue through Burchetts Green to meet the A4 a mile or so west of The Thicket.

This was declassified at the same time to placate locals who were fed up with it being used as a rat run. ( I always used it as such until some vicious sleeping policemen were installed a few years later).

The underpass at the Thicket roundabout was built at the same time as the DC link. The original A423 road was realigned to a new mini roundabout to the east for local access.

Simon Hardy has some news about the modern-day signage:

If you go through Woodlands Park, the signage still has A423(M) obviously ones that were missed (and not been clonked by a car).


Maidenhead Bypass




1 miles

1.6 km





Map Links:

Might Have Been Map

Present Day Map