Sales of Buckfast have hit new heights but Brexit has eaten into profit margins, according to the tonic wine maker’s newly filed financial accounts.

Annual accounts for owner J Chandler & Co for the year to 31 March 2017 show a 3.1% rise in sales to £43.2m on top of an increase of over 15% in its previous year.

This slowdown is partly due to sales in the previous financial year having been boosted by customers stocking up ahead of a March 2016 duty rise. But J Chandler forecasts this overall growth trajectory to continue in its current financial year, with director Jonathan Sharp expecting a “modest” turnover increase in 2017/18.

However, he noted that the bottom line would continue to be affected by the weakness of sterling.

Pre-tax profits for the year rose by over 21% to £4.3m, but this was largely driven by almost £1m of interest income.

Operating profits fell 3.3% to £3.4m and operating margin slipped from 8.4% to 7.8%.

Before the 2015/16 financial year, Buckfast’s sales had been relatively stable at £36m-£39m before a focus on expansion outside its traditional Scottish base into England helped boost revenues to over £40m.