Gap Not Wide Enough

Highland Council : Requirements + Shopfront Design Guide
An advertising sign:
- can be placed on the footway only where the width of the footpath allows.
- the remaining available footway width between carriageway and front of display/sign
    must not be reduced below 1.8m;
    not below 2.75m for high pedestrian usage;
    not below 3.5m for pedestrianised area.

Transport Scotland : Good practice
A minimum 2.0m wide obstacle-free passageway is retained

Roads (Scotland) Act 1984 : [Section 59]
"... nothing shall be placed or deposited in a [footway] so as to cause an obstruction ..."

Note: Highland Council's minimum gap of 1.8m
  is narrower than Transport Scotland's good practice guide of 2.0m.
It may be greater for a footway with high pedestrian usage or a pedestrianised area
  but this needs to be properly defined.