The wimpish Frank, sporting his trademark beret and raincoat, was married to the (apparently normal) Betty (played by Michele Dotrice) and in later series they had a baby daughter, Jessica, which offered scope for even more slapstick humour. Frank was a gift for impersonators, and the name "Frank Spencer" may still be used in the UK to refer to a particularly inept man, particularly one who is not very good at home improvements.
One of Frank's catch phrases was a quavering "Ooh... I'm being ha-RASSed!". This gained comic effect by employing a little-used word, pronounced wrongly (compared to the normal UK emphasis, "HArassed"). But Frank's usage has since become common in the UK, perhaps solely from the popularity of this phrase. (See the List of words of disputed pronunciation.)