With historical Hansard fully searchable by speaker and party for the first time, thanks to the ‘Digging into Linked Parliamentary Data’ project based at the Institute of Historical Research, it is now possible easily to explore how particular issues have been discussed in the House of Commons over decades and even centuries, explains Jane Winters, professor of digital humanities at the School of Advanced Study.

Debate about Britain’s future in the European Union is currently occupying both parliament and the media, but this year a decision will also have to be made about whether to renew Britain’s Trident nuclear weapons programme.

‘Trident’ appears surprisingly frequently in Hansard, in a total of 4,858 speeches between 1803 and 2013­–14 (the period covered by the new database). Apart from a handful of literal three-pronged tridents, there are four distinct types of mention: the metaphor of the trident, often in association with the figure of Britannia; references to various naval vessels named Trident; discussion of the Hawker Siddeley Trident aircraft, used by the state-owned British European Airways Corporation (BEA); and finally the Trident nuclear programme announced in 1980.

The metaphor, of course, predominates in the early period, and is rarely understated: ‘For the first time in our history we are mendicants. The symbol of Britain is no longer the proud Trident of Britannia, but the begging bowl’ (David Gammans, Conservative, 1948). This metaphorical use is also, however, associated with the Trident nuclear programme in later years, perhaps too tempting a rhetorical connection to be left unmade: ‘The case for Trident has not been made strongly. We have had several facile phrases … We have the weapon of last resort. That is a chilling phrase which conjures up a romantic but gruesome image of Britannia and her trident with her back to the sea and with Europe apparently in ruins and America either defeated or sulking in her tent’ (Denzil Davies, Labour, 1986).

Restricting the search to the period from 1980 to the present day removes only 383 of these references, so it is reasonable to assume that the vast majority of the remaining mentions of ‘Trident’ relate to the nuclear weapons programme. The term has been used in the House of Commons almost equally by speakers from the Labour and Conservative parties, in 1,925 and 1,909 speeches respectively. This is perhaps to be expected, as whichever party formed the government of the day would respond to questions and interventions from the main opposition in a roughly balanced exchange.

More interesting are the terms most commonly associated with ‘Trident’, along party lines. There is considerable overlap between the main three parties, for example the prominence of ‘defence’, but there are subtle differences too: Labour MPs are more likely to mention Trident in the context of ‘commitment’ and ‘cost’, while for the Conservatives emphasis on ‘deterrent’ looms particularly large. All parties, however, speak of ‘replacement’ and ‘alternatives’ (without further investigation it’s not possible to say whether this is positive or negative). All that might be said is that discussion about Trident is most frequent when decisions have to be made about its future.

Turning to individuals rather than parties, the three speakers who have mentioned Trident most often in the Commons are all Labour MPs: Bob Cryer (former MP for Bradford South), the above-mentioned Denzil Davies (former MP for Llanelli) and Jeremy Corbyn (the current Labour leader).

Corbyn’s first reference to Trident occurs in a debate about pensioners’ gas and electricity bills, and specifically the abolition of standing charges. In contrast to ‘the horror and poverty that many pensioner households face day in, day out, and the fear that many of them have about heating their homes adequately or even cooking a hot meal on a cold evening because they cannot afford the bill’, he notes ‘It is amazing that, in a few moments, the Secretary of State for Defence will be telling us of the bottomless pit that defence expenditure has become. The cost of just one quarter of the Trident programme will be £2.5 billion’ (1985).

All three MPs are firm opponents of the Trident programme, but they are followed in the list by two Conservative secretaries of state for defence, John Nott and George Younger (former MPs for St. Ives and Ayr respectively) who, of course, take a different view. They are concerned both to play down the cost of Trident and to emphasise the job losses that might result from its abandonment: ‘I realise that if the political parties in this country have taken up a position that is antagonistic to Trident, there is not a lot more I can do to persuade them. But the amount of money that Trident will cost us in the next few years is not more than a couple of hundred million pounds on average, against a total budget of £12½ billion’ (Nott, 1981); ‘The policy of the Labour party is to close down the Trident and Polaris programmes, which means that if there were again to be a Labour Government, which is extremely unlikely, there would be a jobs disaster at both Rosyth and Faslane’ (Younger, 1985).

Hansard reveals that there has been vigorous and often bitter debate about Trident from the 1980s to the present day, albeit with noticeable peaks and troughs (414 separate debates in 1982 but only seven in 2001). It is coming firmly back on to the agenda this year, with a new Labour leader who has been opposed to it throughout his political career and a Scottish National Party with a record number of MPs in the Commons and a distinct political and geographical interest in the decision about renewal.

There were 125 debates in 2013–14, with the last word on the subject going to Martin Horwood (former Liberal Democrat MP for Cheltenham), raising the prospect of a different kind of threat to national security: ‘Trident addresses a theoretical and perhaps quite real future risk, and there are different views on that, but the cyber-security programme is defending us against current ongoing attacks’ (2014).

It seems inevitable that the upward trend will continue this year, and that Jeremy Corbyn is likely to remain one of the MPs who most frequently discusses the issue. It will be fascinating – and now easily possible – to look back on this new debate, and compare the terminology and the personnel with the original discussions about the programme in the early 1980s.

You can explore this and other subjects in historical Hansard, along with the proceedings of the Belgian, Canadian, Danish, Dutch, Norwegian, Swedish and European parliaments. The project was funded by the Digging into Data Challenge.

Professor Jane Winters is responsible for developing digital humanities at the School of Advanced Study. She has led or co-directed a range of digital projects, including most recently Big UK Domain Data for the Arts and Humanities; Digging into Linked Parliamentary Metadata; Traces through Time: Prosopography in Practice across Big Data; the Thesaurus of British and Irish History as SKOS; and Born Digital Big Data and Approaches for History and the Humanities. Her research interests include digital history, web archives, big data for humanities research, peer review in the digital environment, text editing, the use of social media in an academic context, e-repositories, and open access publishing.