Looks like fairly recent established population that came in on track.
Cytisus scoparius; common by side of track
Late summer so just dried up pods now.
Still on the summit
Cytisus scoparius, the common broom or Scotch broom, syn. Sarothamnus scoparius, is a perennial leguminous shrub native to western and central Europe. In Britain and Ireland, the standard name is broom, but this name is also used generically for other related species (see broom), and the term common broom is sometimes used for clarification. In other English-speaking countries, the most prevalent common name is Scotch broom (or Scot's broom); English broom is also occasionally used.