Sources

Where the facts come from

Every factual claim on this site links to its source. This is the full list.

How we checked

Each fact was written in our own words alongside its source. Our build script stores the text of every source and, for each fact, checks that the key words and figures really appear in it. 168 of 168 checks passed when this site was last built (10 November 2026). Where we couldn’t find a named source saying something, we left it out. Where good sources disagree, we say so and give both.

Where sources differ

Big Ben’s weight. 13.7 tonnes (Parliament facts page; Parliament news, 2017) or 13.5 tonnes (Parliament’s clock-history page).
The Great Clock’s weight. 5 tonnes for the mechanism (facts page), 11 tonnes (news, 2019), eleven and a half tonnes for over 1,000 parts (Cumbria Clock Company, via Parliament, 2021) or 12 tonnes (conservation page).
The pendulum. 310 kg (facts page) or 170 kg (Cumbria Clock Company, 2021).
Dial diameter. 7 m (facts page) or 6.9 m (tour page).
The Ayrton Light. Installed 1885 (Parliament news, 2021) or the permanent light installed 1892 (history page, and the same news story).
When the restoration finished. 2022 (key dates page; bells and exterior, November 2022) or October 2023 for the whole project (Finance Committee note). Due in 2021 when reported in 2019.
The name. In honour of Sir Benjamin Hall (The Times, 1856), probably named after him in fun (Parliament), or the boxer Ben Caunt (a theory reported by HISTORY, which prefers Hall).

How we checked

Where sources differ

All sources (30)