21/22 + bank hols.  Increases after 3/5 years service or something like that.  But up to 2 days flexitime per month allowed if you've worked unpaid overtime.  can carry over up to 5 per year.
My first job was 23, increasing by 1 for each year of service up to a max of 5.  On top of that, we had a flexible benefits package where you could buy/sell hols, up to 5.  So, we could have 33 + bank hols, which was amazing.  Could also carry over up to 5 per year.
Not come across another engineering consulting company that does the same sadly.