Accessibility issues with multi-select dropdown

[cjrace]

Describe the bug
Flagged in testing as a WCAG failing as the multi-select was problematic for screen reader users as the expected behaviour is not intuitive and elements have not been created using the correct mark-up.

Screenshots

Additional context

From the design system - https://design-system.service.gov.uk/components/select/

Avoid adding functionality to allow selecting multiple options. The select component does not support selecting multiple options, as there’s a history of poor usability and assistive technology support for select multiple - https://www.24a11y.com/2019/select-your-poison

If you need to ask the user to pick more than one item from a list, it’s almost always better to use another method, such as a list of checkboxes.

WCAG 2.2 - Any input that’s designed to let a user select multiple options must offer a way to do so without relying on ‘click and drag’ movements or keyboard and mouse combination actions.

This is to comply with WCAG 2.2 success criterion 2.5.7 Dragging movements.

Suggestion

We look into alternatives, such as checkbox lists to replace this kind of multi-select