This is tufted vetch (Vicia cracca), a species of vetch native to Europe and Asia.
It is a scrambling plant, a legume, a member of the pea family. Its leaf stems end with tendrils that it uses to hold on to other plants. Its height depends on the height of the plants it is climbing through. In a tall sunny hedge it can reach three metres; in the set-aside at the top of Village Green it grows as tall as the grass and at the end of Lambrok Meadow, where these photographs were taken, it is growing as tall as the nettles.
In the past it was grown for fodder and as such, colonists took it around the world with their stock. Outside of its home range, it can easily out-compete native plants and become a problem; in America is is considered an invasive weed, detrimental to traditional prairie grasslands.
Here among the park’s grass and in its hedges, it is a bright and welcome show of colour, full of bumble bees.