During the protest, slogans were painted on the wall of the Grade II-listed building and on the pavement in front of the steps.
Dating from the 1930s, it originally housed the UK government’s Welsh Board of Health.
After the position of secretary of state for Wales was created in the 1960s, it became home to the Welsh Office.
Then In 1999, it became part of the office complex used by Wales’ fledgling devolved government.
Campaigning for and promoting the Welsh language was a feature in ap Iorwerth’s formative years.
His father Edward Morus was a teacher, prominent singer and composer, as well as being an active campaigner for Plaid Cymru, the Welsh language and Welsh culture.
Ap Iorwerth literally means son of Iorwerth – Iorwerth being a Welsh form of Edward.
The first minister’s mother was also a teacher and went on to become president of several organisations promoting the Welsh language.