Newton, a copywriter, and Richards, an art director, join from Partners Andrews Aldridge, where they spent the past four-and-a-half years.
During this time, they worked across a number of the agency's flagship accounts, including The Art Fund, Lex-us and bmi, and were involved in successful pitches for Wales Tourist Board and COI.
Awards they have collected include two silvers at last year's Campaign Direct Awards ceremony for their "resignation letter" mailer for Video Arts.
The pair were also presented with a D&AD student award while at Buckinghamshire College, from where they joined Partners Andrews Aldridge.
In their new job, they will report to the Rapier creative director, David Prideaux. He said: "We're moving to the advertising equivalent of total football - creative teams need to feel comfortable in every different channel or discipline. Plenty of writers and art directors say they can do this. Ross and Sarah actually have the work to back it up."