Windsor Triathlon - fecking knobends!!!!

[DaveReading]

The HC says you shouldn't ride more than two abreast on narrow roads (IIRC, it's not like I check it on a regular basis).  Not sure if that is a narrow road or what classifies as a narrow road.  Also can't remember if the wording is "must" or "should".

"Must" in the HC normally means the provision is backed by a law.  There is no law preventing riding more than two abreast.

[Frank9755]

It is 'should'.
For context, these are other'shoulds':

   You should wear

    a cycle helmet which conforms to current regulations, is the correct size and securely fastened
    appropriate clothes for cycling. Avoid clothes which may get tangled in the chain, or in a wheel or may obscure your lights
    light-coloured or fluorescent clothing which helps other road users to see you in daylight and poor light
    reflective clothing and/or accessories (belt, arm or ankle bands) in the dark.

Not riding on pavement is a 'must'
 
http://www.highwaycodeuk.co.uk/rules-for-cyclists.html

[David Martin]

A narrow road was typically one where a car could not pass you if you were riding two abreast, so a single track with passing spaces would be a narrow road. If there is a dividing white line one would not consider it a narrow road in this context. The reasoning then about singling out around corners makes sense as there would not be space for a car coming the other way to pass you if you were two abreast.
This seems to have been reinterpreted int eh minds of motorists to think that narrow means they have to cross the white line to pass.