How long would

[Robbadob]

Is this question correct?

How long would it take to travel from the furthest-north city in the UK to the furthest-south (one/city/neither?)?

 

[tedmc]

There are northernmost and southernmost you can use.

 

[Tarheel]

Try:

How long would it take to travel from the northernmost city in the UK to the southernmost city in the UK?

(Cross posted.)

 

[Robbadob]

Is it necessary to repeat "city in the UK"?

 

[tedmc]

Is it necessary to repeat "city in the UK"?

Northermost/southernmost city would be enough if the listener knows which country you are talking about.

 

[GoesStation]

I'd say How long does it take to get from the northernmost city in the UK to the southernmost one? My interlocutor would naturally respond by asking how I'm thinking of traveling — by car, by train, on foot, etc.

 

[emsr2d2]

I'd say the same as GoesStation but without "one" at the end.

How long does it take to get from the northernmost city in the UK to the southernmost?