Of the estimated 30 billion food miles associated with UK consumed food, 82 per cent are generated within the country

Of the estimated 30 billion food miles associated with UK consumed food, 82 per cent are generated within the country, and over half of those in 2005 were simply due to trips by car from homes to local food shops. 

… 

Buying a locally reared Welsh lamb in the UK is worse for the environment than buying a frozen one. Indeed, lamb which is imported 11,000 miles from New Zealand is, somewhat surprisingly, better for the environment and has a lower carbon footprint. The impact of food transport can be offset, to some extent, if food production is more sustainable than local production methods.

T. Spector, Spoon fed (2020), 209-10