Table 1

Variables used in analyses, their definitions and categories if applicable

VariableDefinition/categories
Cigarette smokingBinary: yes, if stated: ‘I smoke cigarettes (including hand rolled) every day’, or ‘I smoke cigarettes (including hand rolled), but not every day’ to the question: ‘Which of the following best applies to you?’
Smoking menthol cigarettesBinary: yes, if cigarette smoking (see above) and stated ‘Tobacco and menthol’ to the question: ‘Cigarettes can be sold in different flavours. They can also be flavoured by capsules, filter tips, cards inserted into a packet or flavoured rolling papers. How would you describe the flavour of the cigarettes you usually smoke/smoked?’
Smoking flavoured cigarettesBinary: yes, if cigarette smoking (see above) and stated ‘Tobacco and menthol’ or ‘Tobacco and some other flavour’ to the question: ‘Cigarettes can be sold in different flavours. They can also be flavoured by capsules, filter tips, cards inserted into a packet or flavoured rolling papers. How would you describe the flavour of the cigarettes you usually smoke/smoked?’
Purchasing sources*Question: ‘In the last 6 months, have you bought any cigarettes or hand rolled tobacco from any of the following?’
Answer options:
  1. Newsagent/off-licence/corner shop

  2. Petrol garage shop

  3. Supermarket

  4. Cash and carry

  5. Internet

  6. Pub (behind the bar)

  7. Pub (vending machine)

  8. Pub (somebody who comes round selling cigarettes cheap)

  9. People who sell cheap cigarettes on the street

  10. People in the local area who are a trusted source of cheap cigarettes

  11. Buy them cheap from friends

  12. Buy them from abroad and bring them back with me

  13. Newsagent/off-licence/corner shop—‘under the counter’

  14. Friends/family bring from abroad

  15. Tobacconist


Further, categorised into three groups:
  • Licit: answer options 1–6, 15

  • Illicit: answer options 7–11, 13

  • Cross-border: answer options 12, 14

GenderCategorical: female, male or non-binary (due to the small proportion of participants who identified as non-binary, they were excluded from regression analyses)
AgeNumerical: modelled using restricted cubic splines with three knots placed at the minimum, median and maximum for age48 49
NationCategorical: England, Scotland, Wales
Social gradeCategorical: measure of socioeconomic position using the National Readership Survey’s classification50 categories: ABC1 (high and intermediate managerial, administrative, or professional, supervisory, clerical, and junior managerial, administrative or professional) or C2DE (skilled manual workers, semi and unskilled manual workers, state pensioners, casual or lowest grade workers, unemployed with state benefits only)
  • *In the study protocol, answer option 7 ‘Pub (vending machine)’ was incorrectly classified as licit, and 14 ‘friends/family bring from abroad’ and 15 ‘tobacconist’ were not listed.