It's an evening, sit down dinner thing, 7 till 9pm, need to use public transport to get there though as we're coming from the midlands on the train so need to also not stand out like a sore thumb while travelling
update - do was last night, it was the bp portrait award dinner. in the end i went in a brown mary portas dress, with a cream shawl and cream shoes. its a dress i already have, love it but don't often wear it. was a bit unsure of my choice when we left home but when we were there it was fine for the occasion.