Saunders Roe SR177? Bristol 188?
SR177 never flew.
Bristol T188 was useless even as a research aircraft. According to a colleague who was involved in the programme, by the time it had reached altitude and set up for a test run, there was barely time for a single test point before it had to come home on fumes.... 260KIAS take-off speed with about 20-25 min endurance, it could only manage about 2 minutes at M2.0. Looked nice though: