‘within three weeks’
If so, it seems pretty unlikely to me that the people negotiating can be doing much in terms of modifying things from the pre-tariff situation, and Trump is likely to do what he did with NAFTA->USMCA
change very little, and then spend time giving the impression to supporters that he's drastically modified the trade environment (Fox News: "Trump has solved our trade problems that Biden permitted to happen with the best trade deal ever"). I mean, trying to complete any kind of meaningful free trade agreement tends to take far longer than that.
Table 1 Duration of US free trade agreement negotiations (in months)
US FTA partner From launch date to signing From launch date to implementation Jordan 4 18 Dominican Republic 6 37 Bahrain 7 30 Oman 10 45 Korea 13 69 Australia 14 22 Israel 15 29 Morocco 16 35 Costa Rica 18 71 El Salvador 18 37 Guatemala 18 40 Honduras 18 38 Mexico 18 31 Nicaragua 18 38 Canada 20 32 Peru 23 56 Singapore 29 37 Chile 30 36 Colombia 31 96 Panama 38 102 Average 18 45
On top of the fact that this would be off-the-charts short for a meaningful FTA in any case, neither of the two "shortening" conditions that were found exist here; it is not a US election year, and while the UK is nominally a monarchy, the monarch holds no power and Parliament is, no doubt, going to be involved in any substantial change in trading relationship.
Despite the small sample, two variables are significant in explaining the delay between launch and signing.
- A king. Having a monarch reduces the length of negotiation by about half. Only four agreements took less than a year, and three were with Bahrain, Jordan, and Oman. A king surely has more leeway to carry out reforms he deems reasonable. (The fourth was the Dominican Republic’s negotiation to join the Central American Free Trade Agreement or CAFTA, though it benefited from joining late, which may suggest that late entrants to an already negotiated TPP could also face shorter delays.)
- An election year. Agreements that are signed in a US presidential election year end up taking about 40 percent less time than agreements signed in other years. This makes sense: Negotiating presidents want to close agreements that they started, which will be part of their legacy. The urge to close is real: More than half of the US agreements were signed in election years and of course the TPP, if implemented, will add to that group.
In the UK's case, there was some prior discussion about a UK-USA FTA, so maybe they could bootstrap off that to reduce the negotiation time, but I have a hard time believing that even an administration-friendly, Republican-majority Congress is going to sign off on whatever the Trump administration negotiates in a major FTA without having some kind of input.
https://en.wikipedia.org/wiki/United_Kingdom%E2%80%93United_States_Free_Trade_Agreement