Crossing the bridge to look up at the mast behind the Castle Green at close quarters (definitely a mast but surely not enough of a Matterhorn). Jogging round the boundary of the steep little field between the railway line and the mast (looking for a way through but not finding one) and then taking the narrow stone ginnel with its mini handgate down to Parkside Road.
Running down Parkside Road, turning right along Larch Grove, then left along Willow Grove to find the tunnel under the (other) railway line through to the Castle estate. Running back to Parkside Road to cross it and then run along the ginnel under the eastern slopes of Aikrigg back to where it turns left and rejoins Valley Drive, and then following Valley Drive to the passage cutting through to the Heron and back home the usual way from there.
Conditions: a cool sunny evening.
Pub? Well C-19 and without T and Monday night so no beer at all!