Silence Therapeutics Appoints New Vice President of Research

Move Bolsters Scientific Team at Company's Research Center in Berlin

LONDON, May 5, 2010 - Silence Therapeutics plc (AIM: SLN) ("Silence" or the "Company")
announces the promotion of Jorg Kaufmann, Ph.D., to the position of vice
president of research. In this new position, Dr. Kaufmann, who previously
served as senior director, technologies at Silence, will play a key role in
overseeing the Company's broad range of RNA interference (RNAi) research
activities, including those focused on advancing Silence's novel small
interfering RNA (siRNA) delivery technologies. Dr. Kaufmann will continue to
be based at Silence's Berlin research center, where the Company recently
announced it is consolidating all research activities related to its novel
RNAi therapeutic platforms.

Dr. Kaufmann possesses more than 13 years of biotechnology industry
experience in both the United States and Europe. Since joining Silence in
2000, he has served as both senior and associate director, technologies at
the Company's Berlin location. Prior to joining Silence, Dr. Kaufmann was a
senior scientist at Chiron Corporation, where he was responsible for leading
one of the company's molecular biology research groups focused on breast
cancer. From 1996-1997 he served as a group leader at the Institute of Tumour
Biology (IMT) in Marburg, Germany. Dr. Kaufmann was a postdoctoral fellow at
the Howard Hughes Medical Institute, University of California, Los Angeles
and received his Ph.D. in molecular biology from the Philipps University
Marburg.

"In his time at Silence Dr. Kaufmann has proven himself a valued member
of our research team, playing a significant role in advancing a number of our
novel RNAi technologies including proprietary RNAi delivery platforms and
innovative approaches siRNA structural modification," stated Klaus Giese,
Ph.D., Silence Therapeutics' chief scientific officer. "The ongoing successes
achieved by our team of scientists in Berlin combined with the consolidation
of all research activities to our Berlin location, has created a need to
continue to strengthen our research organization. To this end, we are pleased
to have him assume the role of vice president of research and look forward to
his continued contributions to strengthening Silence's position as a leader
in the RNAi sector."

About Silence Therapeutics plc (www.silence-therapeutics.com)

Silence Therapeutics plc (AIM: SLN) is a leading global biotechnology
company dedicated to the discovery, development and delivery of targeted,
systemic RNA interference (RNAi) therapeutics for the treatment of serious
diseases. The company possesses multiple proprietary siRNA delivery
technology platforms including AtuPLEX(TM), a system that enables the
functional delivery of siRNA molecules to targeted diseased tissues and
cells, while increasing their bioavailability and intracellular uptake. A
second, complementary delivery technology known as PolyTran(TM) uses a
library of novel peptide-based biodegradable polycationic polymers for
systemic siRNA administration. Additionally, the company has a platform of
novel short interfering RNA (siRNA) molecules, AtuRNAi, which provide a
number of advantages over conventional siRNA molecules, including increased
stability against nuclease degradation. Silence's unique RNAi assets also
include structural features for a next generation of RNAi molecules and
additional proprietary siRNA sequences against more than 50 highly valued
oncology and other disease targets.

The company's strong and diverse intellectual property portfolio includes
exclusive licenses from the University of Massachusetts on three patent
families associated with the Zamore "Design Rules," which cover broad
structural features of siRNA design for more potent next generation siRNA
sequences.

Silence Therapeutics is headquartered in London, UK, with research and
development operations in Berlin and Palo Alto, CA.

Forward-Looking Statements

This press release includes forward-looking statements that are subject
to risks, uncertainties and other factors. These risks and uncertainties
could cause actual results to differ materially from those referred to in the
forward-looking statements. All forward-looking statements are based on
information currently available to Silence Therapeutics and Silence
Therapeutics assumes no obligation to update any such forward-looking
statements.

Phil Haworth of Silence Therapeutics, +1-650-855-1514, p.haworth at silence-therapeutics.com; or Richard Potts, or Jonathan Senior, both of Nomura Code Securities, +44-020-7776-1200, for Silence Therapeutics; or media, Tim Brons, +1-415-675-7400, tbrons at vidacommunication.com, or investors, Stephanie Diaz, +1-415-675-7400, sdiaz at vidacommunication.com, both of Vida Communication for Silence Therapeutics