RoMo Coffee (Ro = Roasting, Mo = Mobile) is a small mobile coffee chain with carts in a few locations around London.
I have come across two of their sites so far (Marylebone Church on the Marylebone Road, near Regents Park; and St Mary Aldermanbury near the Barbican), both on cold days when the sight of them was most welcome. The coffee was hot and tasty, and the service was friendly and welcoming.
The outlets are generally open Monday to Friday, but are also open at weekends for certain special events.
Linked to Sundays in my City.