The Britannia Pub on 3rd Street is a reliably comfortable bar in the centre of Santa Monica — unpretentious, well-supplied with draught beers, and with outdoor seating that makes it usable for most of the year in this climate. The interior leans into the British pub aesthetic without being embarrassing about it; the menu runs to fish and chips and burgers.
It is the kind of place where you end up rather than seek out, usually after something on the Promenade. That is not a criticism. A reliable, decent bar within walking distance of everything is genuinely useful, and the Britannia fills that role without drama.