Pathetic Motorways, and the "Walton Summit Motorway" 

I resent the implication, being the webmaster of the aforementioned site.  The site is not a "Wacky Website", but a factually accurate record, with comments tossed in.  You are allowed to educate without boring people, you know!

UncleG is proceeding from a false assumption:  that the classification of all motorways is listed on signposts.  There are many other examples of "unsigned" motorways where official DfT documentation exists, such as the tiny A635(M) in Manchester or the A14(M) in Cambridgeshire.

The Walton Summit Motorway is an extremely unusual case.  Whilst it is quite true that there are many short motorway spurs that are simply a part of the "parent" motorway, such as the M1 spur at Luton, the Walton Summit Motorway does not fall into this category.

As is clearly pointed out, the Walton Summit Motorway is neither part of the M61, nor part of the M65, but does have motorway classification because it inescapably leads to the roundabout that links the two.  There is no other stretch of motorway in the UK where a short "spur" motorway actually links two different motorways.

If it is part of the M65, as the "start of restrictions" sign at the bottom of the hill implies, then why does the directional flag sign state "M61 (M65)", meaning a part of the M61?  This is a common form of signage throughout the UK system, but is unusual to be found upon a motorway.  

A similar item can be seen with reference to the example of the A635(M) above, the "start of restrictions" sign when heading westbound on the A635(M) clearly states "A57(M)", but the DfT documentation states otherwise. (it's the "Statutory Instrument 1995 No. 3266 The City of Manchester (Mancunian Way A635(M) and A57(M) Mancunian Way Slip Roads) Special Road Scheme 1992 Confirmation Instrument 1995" that you're looking for if you're really concerned about its accuracy.  A PDF copy is available on Pathetic Motorways, but a simple Google search will turn up the relevant central government pages if you doubt the source material).

The Walton Summit Motorway is a motorway without a number, hardly an unusual concept in road terms, where most roads either do not possess a classification number, or is of a "C", "D" or "U" classification, which do not appear on road signs.  It is, bowever, an unusual concept in motorway terms.