I think some of the separately mapped sidewalks in here are a bit incomplete - see for example osm.org/directions?engine=fossgis_valhalla_foot&route=53.634039%2C-2.815702%3B53.634007%2C-2.815523#map=19/53.634189/-2.814973 .
If it was me, I'd just use "sidewalk=left" or similar here; if you're going to use separately mapped sidewalks you need to make sure that you join everything up.
Best Regards,
Andy

After editing any paths involved in a hiking route relation (e.g. all the coastal ones!) it makes sense to check http://ra.osmsurround.org/analyzeRelation?relationId=77964&noCache=true&_noCache=on (where 77964 is the relation) so that it matches what is signed on the ground. There are obviously genuine duplications (high and low tide, whether paths across the ranges are open etc.) but there are some very dubious spurs still.