Yellow plant in garden in Twickenham

Yellow plant in garden in Twickenham

Observation - Yellow plant in garden in Twickenham - UK and Ireland. Description: Has appeared as a yellow flower spike thrown up from foliage in a couple of spots in the garden in the last two weeks or so. Quite attractive. Have I gaineda new plant or is it a weed likely to take over?

Has appeared as a yellow flower spike thrown up from foliage in a couple of spots in the garden in the last two weeks or so. Quite attractive. Have I gaineda new plant or is it a weed likely to take over?