I will add that we are extremely rigorous in reminding departments that they cannot spend a penny without Parliament's having voted in the year, so even when a government makes an announcement of an intention to spend within the year--let alone in future years--unless those funds were specifically provided in the main estimates, departments must wait until the supplementary estimates. Multi-year budget plans are just that: they must be voted year by year.
On June 13th, 2006. See this statement in context.