The true effect of the lockdown on alcohol intake remains unknown. 2 months after lockdown was declared in the UK (March 23, 2020), we did a cross-sectional telephone survey of 182 patients with pre-existing alcohol disorders registered since 2017 in the alcohol clinic of St Mary’s Hospital, London. Participants were mainly male (73%) and of white ethnicity (78%), with a median age of 57 years. Of the 182 participants, 24% reported an increase in their alcohol intake, with a mean increase in the AUDIT score of 57.6%, and a mean weekly consumption of 82.5 units. 19% reported a decrease in their alcohol intake. 38% patients were classified as abstinent before lockdown, of this subgroup, 17% relapsed during lockdown. Of the 113 individuals who were previously drinking before the lockdown, 12% became newly abstinent since the beginning of lockdown. Nonetheless, these findings should be interpreted with caution because of the small sample size of this subgroup. Lockdown represents a risk factor for increasing alcohol consumption in people with alcohol use disorders and relapse for those who were previously abstinent. Those who do relapse are at a high risk of harmful drinking and require a tailored approach for follow-up and intervention. Support from alcohol liaison services could prevent relapse during lockdown; any further changes that might present if lockdown conditions change remain to be elucidated.