Whilst out and about in Cornwall today - St Issey, nr Wadbridge, I saw a Thomson plane flying what appeared to be very slowly, so probably quite a large a/c. As soon as I completed my work, I hacked down the A39 towards Newquay, and saw the aircraft with wheels down climbing out of Newquay/RAF St Mawgan and doing circuits and approaches, so I assume on a crew familiarity and training flight. When I got to Spitfire Corner (for those in the know - a 4 blade prop ~2/3 scale non-flying replica) I could see the Thomson a/c stationary on the ground, and I was directly in front of it at about 1/4 mile distance, and could the a/c was huge, I would guess the tailplane top would be 45 - 50' agl? All I could hear was a fairly high pitched whistle from the 2 engines, but very quiet compared to most airliners. Anyway, after about 10 minutes and a couple of smaller a/c landing, including an IoS sky bus, power was applied and the a/c came towards me and turned to starboard, and I could see its reg G-TUIB and the Dreamliner log and name - and without bins it looked like the name Alfie on the port side near cockpit. What a massive a/c it is!. It turned onto the main runway, then a lot more power was applied and it went on along the runway and took off. What I'm absolutely gob-smacked about, was how quiet the engines were even for a fairly high power take-off, talk about a whispering giant, there was quite a bit less noise behind it whilst taking off than when it was idling. Talk about a whispering giant! Unbelievably quiet and surprisingly graceful.