The combination of aerodrome control and radar has been done for years (probably over a decade) outside of the UK. If it works there, why not in the UK?
Not directly related to TBS, but I think if the safety case has been proven in practice for years outside the UK and approved byt he CAA, then it can be considered to be acceptable.
So you have one concept which was proven before it was brought in the UK, still there are many doubting wether it will work.
Then you have a concept (TBS) which has been designed from scratch, within the UK, and still the same doubts arise?
To very different developments met with the same response, what did they both do wrong in order to get that response?