Potter Clarkson makes gains in both prosecution rankings this year, reaching the coveted top tier of patent prosecution. Although with the one Nottingham office, the patent firm is "a great firm... and doing well", note peers. With a substantial presence and reputation for patent work all over Europe, the firm provides exemplary service to prominent companies such as AstraZeneca, GlaxoSmithKline and Nokia. One of the strengths of the firm is its personnel, with peers agreeing that the "good people" there set the firm apart in terms of quality and performance. Anki Malmborg of LU Bio in Sweden has high praise for partners Stephen Smith and Philip Thomas: "We completely involve them in every way and they handle all our filings and freedom-to-operate work. What I like is that they write patents with potential trials in mind and they give us a full status report every six months." A continuing matter for the patent team is its representation of client AstraZeneca before the EPO for oppositions relating to the patents for the client's product Nexium, which is one of the world's best-selling drugs with $5 billion in sales in 2009.