diff --git a/Code/Mantid/Framework/API/inc/MantidAPI/FunctionParameterDecorator.h b/Code/Mantid/Framework/API/inc/MantidAPI/FunctionParameterDecorator.h
index edbd2d70d720f478be2b95e0904ebe1ab1e1a525..533c9942cdd251169ddc1fa24ea1386ef566d14b 100644
--- a/Code/Mantid/Framework/API/inc/MantidAPI/FunctionParameterDecorator.h
+++ b/Code/Mantid/Framework/API/inc/MantidAPI/FunctionParameterDecorator.h
@@ -64,6 +64,12 @@ public:
   /// Set description of parameter of decorated function by name.
   virtual void setParameterDescription(const std::string &name,
                                        const std::string &description);
+
+  /// Value of i-th active parameter of the decorated function.
+  virtual double activeParameter(size_t i) const;
+  /// Set new value of i-th active parameter of the decorated function.
+  virtual void setActiveParameter(size_t i, double value);
+
   /// Get parameter of decorated function by name.
   virtual double getParameter(const std::string &name) const;
   /// Total number of parameters of decorated function.
diff --git a/Code/Mantid/Framework/API/src/FunctionParameterDecorator.cpp b/Code/Mantid/Framework/API/src/FunctionParameterDecorator.cpp
index c2fb3100429099340b5b97c87b2c5b5840bf3cf1..fce40a88b01593bf7d223c202981e8bd75e95d8e 100644
--- a/Code/Mantid/Framework/API/src/FunctionParameterDecorator.cpp
+++ b/Code/Mantid/Framework/API/src/FunctionParameterDecorator.cpp
@@ -72,6 +72,18 @@ void FunctionParameterDecorator::setParameterDescription(
   m_wrappedFunction->setParameterDescription(name, description);
 }
 
+double FunctionParameterDecorator::activeParameter(size_t i) const {
+  throwIfNoFunctionSet();
+
+  return m_wrappedFunction->activeParameter(i);
+}
+
+void FunctionParameterDecorator::setActiveParameter(size_t i, double value) {
+  throwIfNoFunctionSet();
+
+  m_wrappedFunction->setActiveParameter(i, value);
+}
+
 double FunctionParameterDecorator::getParameter(const std::string &name) const {
   throwIfNoFunctionSet();