To find each of the restaurant locations, Google Maps and Search were used. A Google Search for each of the restaurants in every city was made, and Maps was used to check whether the listed locations had a drive-thru. In the case of an unclear or questionable listing, Street View was used to manually verify whether the location had a visible drive-thru.
In our research, we used the projected ONS population. The drive-thru restaurants referenced are those within easy driving distance of the town centre.
https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/populationestimates/datasets/analysisofpopulationestimatestool
This methodology uses the logic that most customers will travel by car to a drive-thru if the restaurant is within easy reach. It follows that the population of the town or city in question will consider using drive-thru restaurants in a wider area than the town itself. We are confident that each restaurant can be reached easily and with a short journey time. This methodology was consistent across all towns and cities.
For example, to illustrate the point for Middlesbrough, the most distant drive-thru (Stockton On Tees Drive-Thru McDonald's) is 4.8 miles from Middlesbrough town centre. This equates to a 15-minute drive. The Wolviston Services Drive-Thru is 4.7 miles, which is a 13-minute drive. (Distances are taken from McDonald's restaurant locator. Driving time is taken from Google Maps - to calculate the most direct route time from the city centre to selected drive thru)