The EU-Japan free trade agreement contains provisions that mean in some instances if Japan (or the EU) does a trade deal with another company that liberalises trade beyond what's in EU-Japan, Japan has to offer same to EU.

BUT they are very limited.

Forward MFN, as it known, applies just to services and investment. And it covers market access issues such as restrictions on number of transactions, or nationality of board members NOT regulatory issues such as licensing.

It is also heavily caveated with lots of exceptions.

For example, it does not apply if there are deep levels of regulatory integration between the two trade partners (for example, the development of a single market).

On tariffs, EU-Japan FTA contains provisions stating that in some specific instances, if J (or EU) decide to phase out tariffs more quickly w/ new FTA partner than with EU (or J), AND it impacts balance of trade btw J & EU, can trigger discussion btw J and EU with aim to match.

So, in conclusion, can people please stop tweeting at me that UK and Japan can't do anything more than Japan agreed with EU "because MFN" because it's much more complicated than that.