Conversation so far:
When did John Bowring become a political economist?
John Bowring had begun contributing to the newly founded Westminster Review and had been appointed its editor by Bentham in 1825.
What was John Bowring's biggest achievement in this area?
By his contributions to the Review John Bowring attained considerable repute as a political economist and parliamentary reformer.
Where was John Bowring living during the time of his career as a political economist?
John Borwing lived in London during his career as a political economist.
What else did John Bowring achieve in this career?
John Borwing was a member of the 1831 Royal Commission.
What did John Bowring do in this role?
As a member of the 1831 Royal Commission, John Bowring advocated strict parliamentary control on public expenditure.

Question: When did he achieve reforms on control on public expenditure?
Self-contained rewrite: When did John Bowring achieve reforms on control on public expenditure?