Question to the HM Treasury:

To ask the Chancellor of the Exchequer, what estimate she has made of the revenue which would be accrued from applying Duty Free allowances to people departing from Great Britain to the European Union.

Allowances are generally not applied to outbound passengers. Instead, goods will be taxed upon arrival in the destination country (subject to any duty free allowances available in that country).

Inbound passengers to the UK are usually entitled to duty free allowances, which allow them to bring in goods up to certain limits without paying UK taxes, providing they are for personal use or to be gifted. Details of those allowances can be found here:

https://www.gov.uk/bringing-goods-into-uk-personal-use/arriving-in-Great-Britain