She also wanted to replace a “rotting wooden door and window frame” with similarly coloured UPVC, a form of plastic used as a wood substitute.
But the plans were refused by Powys County Council planners earlier this month saying UPVC windows in a conservation area were contrary to relevant planning policy.
Fay Jones MP said: “The planning application was made after recommendations by Parliament’s security and policing teams. Our options are limited as the Parliamentary security team have installed measures designed to protect the safety of those working in MPs’ offices.
“All too sadly the murder of two MPs and attacks upon offices, including here in Powys, in recent times has exemplified the need for secure premises.
“We have received a warm welcome since opening the office and hope that we can continue to make ourselves available to the people of the Llandrindod Wells area. Added to which it would be a great shame to see another shop go ‘dark’ in the Town.”
Miss Jones said she would explore all options before making a decision on whether to appeal the decision.