Related Clues:
- Pack of toothpaste; type of train
- Transport system bringing objection around England's capital?
- Long hollow cylinder
- Electrical valve type
- Train and boat, heading for Europe
- Valve container, earliest bit of electronics
- Valve with three electrodes
- Type of thermionic valve
- Underground; pipe
- Pipe; underground train
- Billions invested in weekday train network
- Can of beer (colloquial)
- Thermionic valve
- Monitor type, briefly
- Clinical research trials initially shows images