The value of gilts has been distorted by QE; that was its intention. The return has been suppressed but as a result their value has been inflated, these having an inverse relationship with each other.
The rate of return on corporate gilts has been distorted by central bank measures to suppress interest rates. This was not the intention, maybe, but by increasing demand for these bonds yields have fallen.
The intention of QE was the effect on corporate bonds. The effect on gilts was the method of creating that desired effect.
Jeepers, this guy teaches, right?