The agency carried out polling in the immediate aftermath of the vote on 23 June and found that just 24% of respondents thought the result would have a positive impact on their lives – despite 52% voting to leave the European Union.
In a survey of carried out from 29 July to 1 August, that figure has now risen to 38%. But it also shows that 50% would vote Remain if the referendum was held again today, with a further 13% saying they were unsure, and only 37% still plumping for Brexit.
JWT spoke to 700 people split across five major European countries for the research, "The essence of Britain tracker": the UK, France, Germany, Italy and Poland.
The study also looked at the attitudes of consumers to brands, and pointed to some opportunities for brands thrown up by the current political turmoil:
40% of Brits said they wanted brands to keep them informed about how they are helping Britain to trade globally
33% wanted brands to keep them informed of how they are helping keep Britain connected with Europe
37% wanted brands to invest in local recruitment/hire more local employees
45% felt brands should be communicating positive British values across Europe
On the last point, however, brands may have their work cut out, as the study also revealed a gulf between how Brits see themselves and how they are perceived by continentals.
Tolerant and multicultural?
When asked which attributes best capture the "Essence of Britain" respondents in the UK picked phrases such as traditional, proud, multicultural and open minded.
But these descriptions were not shared overseas. While 28% of Brits thought the country could be described as "fair", this opinion was shared by only 17% of French, 10% of Italians, 9% of Poles and 7% of Germans. With a few exceptions for individual countries, the same discrepancies appeared for multicultural, open-minded, tolerant and equal opportunities.
On the other hand, nationalist was given by 31% of French, 30% of Germans and 39% of Italians – a view shared by only 10% of Brits.
JWT European chief executive Toby Hoare said: "This is very important for British brands or those seen to have a strong British heritage to realise if they are thinking about trading in Europe or expanding their businesses.
"This perception of us as a nation is now the reality that these brands are operating in. People view us very differently to how we view ourselves and they have to adapt their strategies to match this."
JWT London co-chief executive James Whitehead added the findings represented a "huge opportunity" for brands untainted by the political fall-out, as they can give consumers top-to-bottom help and guidance in a post-Brexit Britain.
Whitehead said: "They have the potential not only to transparently and intelligently inform consumers about business, trading and manufacturing both here and in Europe, but can also be the ones to recalibrate this disparity in the Essence of Britain between ourselves and Europe, while also helping them with what is important to them on their doorstep and at a local level."