To be fair, France and the UK are extremely close. I don't understand why either side always try to make people believe something else.
Edit: And India.
Investopedia has us fifth, then India and France. Tbf, you can measure economy size in several different ways, which will throw up different results.
https://www.investopedia.com/articles/investing/022415/worlds-top-10-economies.asp
GDP per head is the more important figure anyway, as far as how prosperous or otherwise people are. I'd rather the lifestyle of the average Swiss than that of an Indian or Brazilian any day.