A presentation to analysts will be held today at 09.30hrs at the offices of Citigate Dewe Rogerson, 3 London Wall Buildings, London, EC2M 5SY.

Please contact Mark Swallow or Yvonne Alexander on 020 7638 9571 for further information. Highlights

Drug Pipeline Progress • Two clinical and three preclinical programmes targeting serious diseases • Phase I clinical trial commenced in Parkinson’s disease and acne • Preclinical candidate in Duchenne muscular dystrophy programme selected Early stage Programme Deals • Multi-million programme collaboration deal signed with Evolva Biotech Profitable Technology Platforms • Gross margins over 60% • Increase in average deal size to £65,000 (H1 2006/07: £30,000) Corporate Highlights • Acquisitions of two UK biotechnology companies in all-paper deals • Re-branding of Company to Summit plc Financial Highlights • Trebling in half-year revenues to £1.4 million (H1 2006/07: £0.47m) as a result of organic growth and acquisitions • R&D investment up to £3.6 million (H1 2006/07: £1.3m) • Cash position of £14.2 million (H1 2006/07: £20.2m)

Barry Price, PhD, Chairman of Summit plc, said “Summit has made a very strong start to the year with excellent progress having been made in all areas of its newly enlarged business. The acquisitions we made early in the year have helped transform Summit and the coming months will be very exciting for the Company: we expect to make significant progress in our two clinical and three preclinical drug programmes; we are working hard towards delivering a major licensing deal for at least one of these programmes; and we anticipate continued growth in the technology platform service business.”

Summit also announced today that it has signed a $450,000 deal with one of the world’s top five pharmaceutical companies for use of its zebrafish technology platform to assess the safety of its proprietary compounds. Please see the separate announcement for further details.

For more information, please contact: Summit plc Steven Lee, PhD, Chief Executive Officer Darren Millington, ACMA, Chief Financial Officer Richard Pye, PhD, Investor Relations Tel: +44 (0)1235 443951

Citigate Dewe Rogerson Mark Swallow / David Dible / Yvonne Alexander Tel: +44 (0)207 638 9571

Evolution Securities Tim Worlledge / Bobbie Hilliam / Neil Elliot Tel: +44 (0)207 071 4300

About Summit plc Summit plc is a leading UK biotechnology company that discovers and develops proprietary new drugs. The Company’s internal drug development programmes are underpinned by its advanced carbohydrate chemistry and drug screening (chemical genomics) technology platforms, which it also provides on a collaborative or fee-for-service basis to the pharmaceutical industry. Summit plc has a broad range of drug discovery programmes in the clinical, pre-clinical and discovery stages of development, which target serious diseases with a high unmet medical need. These therapeutic areas include neuro-disorders (neurodegenerative and neuromuscular), anti-infectives, ophthalmic diseases, oncology and regenerative medicines. Summit plc’s in-house drug development capabilities combine world-class expertise in both carbohydrate chemistry with high-volume, high-content screening using its proprietary zebrafish and fruitfly technologies (chemical genomics). These whole organism screens have the potential to dramatically decrease the time and cost of drug discovery and development by delivering data that are highly predictive of the efficacy and toxicity of potential drug compounds in humans. The company listed on the AIM market of the London Stock Exchange in October 2004 – symbol: SUMM Further information about the company is available at www.summitplc.com