Sorry... quickly found I can, however, the data comes in plain text, and I need rich.
As it happens my partner, who is an archivist, needed to display rich text in a 'citations' combo box in a database which she and I have been developing for a museum in the USA. A combo box cannot in itself display rich text, but you can do so in a 'hybrid' control made up of a text box carefully superimposed on a combo box to appear and act like a single combo box control. The text box is formatted as rich text, and this is what the user sees in the control while its list is not dropped down. The underlying combo box is formatted as plain text, so the user selects a citation from another plain text column in the referenced table. This column returns the first 255 characters of the citation, and is populated by code which strips out all of the rich text tags by means of multiple Replace function calls when a row is inserted into the Citations table.