His work focused on sea level science and as part of this he invented a new class of tide gauge, called a "bubbler", which remains in use to this day in the United Kingdom.

In 1984 Pugh was appointed as Head of Oceanography, Hydrology and Meteorology for the UK Natural Environment Research Council.

[4] Along with American oceanographer Klaus Wyrtki, Pugh proposed and established the Global Sea Level Observing System (GLOSS), a program of the Intergovernmental Oceanographic Commission including real-time tsunami detection and contributing data to the global Permanent Service for Mean Sea Level (PSMSL) repository.

[5] His 1987 book, "Tides, Surges and Mean Sea Level—A handbook for engineers and scientists", has been reported as "used by an enormous number of researchers and students", and received positive reviews as a valuable reference work.

[4][6][7] Following retirement Pugh continued to undertake research into tides and sea level, and was emeritus fellow of the National Oceanography Centre.