Following your suggestions, I have, correctly or incorrectly, settled on Bromus sterilis. Thank you both again.
Consider also possibility of Bromus rubens (syn. Bromus madritensis). Bromus sterilis has drooping branches of the inflorescence, whereas in Bromus rubens, the branches remain ascending. You need to find an older plant with open panicle to tell the difference. Bromus rigidus has also more ascending branches and longer spikelets than Bromus sterilis.