The 2010 Spending Review protected the budget for Science & Research programmes in cash terms at 2010-11 levels - £4.6bn per year - inside a ringfence for the next four years. Capital and administration budgets were not protectected. The letter from BIS to the Royal Society's President spoke of the good result for UK science and thanked the Society for their part in this.
Although the size of the budget has been decided, BIS still have to negotiate the balance between high level funding lines of the Science and Research budget: between the Higher Education Funding Council and the Research Councils, as well as amongst the seven Research Councils.
(Martin Rees's response from the day of the spending review is here)