BACKGROUND AND AIMS: Early evidence suggests that COVID-19 lockdown restrictions affect alcohol consumption. However, existing studies lack data on how drinking practices changed as restrictions disrupted people's work, family life and socializing routines. We examined changes in consumption and drinking occasion characteristics during three periods of changing restrictions in Scotland/England.

DESIGN: Interrupted time-series analysis of repeat cross-sectional market research data (assessing step-level changes). Setting: Scotland/England, January 2009-December 2020. Participants: Scotland: 41 507 adult drinkers; England: 253 148 adult drinkers.

MEASUREMENTS: Three intervention points: March 2020 lockdown, July 2020 easing of restrictions and October 2020 re-introduction of some restrictions. Primary outcome: mean units consumed per week (total/off-trade/on-trade; 1 unit = 8 g ethanol). Secondary outcomes: drinking > 14 units per week, heavy drinking, drinking days per week, solitary drinking, drinking with family/partners, drinking with friends/colleagues, own-home drinking, drinking in someone else's home and drinking start times.

FINDINGS: In Scotland, March 2020's lockdown was associated with a 2.32 increase in off-trade (i.e. shop-bought) units per week, a -2.84 decrease in on-trade (i.e. licensed venues) units per week, but no statistically significant change in total units per week. July 2020's easing of restrictions was associated with a 1.33 increase in on-trade units per week, but no statistically significant total/off-trade consumption changes. October 2020's re-introduction of some restrictions was not associated with statistically significant consumption changes. Results for England were broadly similar. Lockdown restrictions were also associated with later drinking start times, fewer occasions in someone else's home and with friends/colleagues, more own-home drinking and (in Scotland only) more solitary drinking.

CONCLUSIONS: Reductions in on-trade alcohol consumption following COVID-19 lockdown restrictions in Scotland/England in 2020 were mainly offset by increased own-home drinking. This largely persisted in periods of greater/lesser restrictions. The shift towards off-trade drinking involved significant changes in the characteristics of drinking occasions.