Not necessarily in presenting the estimates or presenting information. The U.K. government has just committed itself to having, more routinely, public consultations when it comes to major tax changes, for example, which then will give the private sector a chance to make input and so on. Many parliaments would call it part of their review process of the budget if private sector institutions such as banks, for example, were to testify, or other private sector institutions that provide independent forecasts of fiscal policy or economic data, but this may not be entirely what you referred to in your question.
On March 26th, 2012. See this statement in context.