Here we have a 2008 British Horological Institute (BHI) 150 Flying Tourbillion watch, which was released to commemorate the BHI’s 150th anniversary. It has the 42mm stainless steel case which has the polished finish and straight lug design. It has the silver dial which has the engine turned finish. It has the black roman numerals with the BHI logo at 12 o’clock and ‘BHI 150’ signing to the right-hand side. The sub-second dial is cut out to expose the flying tourbillion, which rotates once a minute and features the sub-second pointer to the tip. It has the luminous index style hour and minute hands, with a chunky crown to the right. There is an exhibition case back which allows you to see the movement finishing. The movement is a Chinese made Liaoning calibre 150 which is keeping time within movement specifications.

It was intended to stimulate interest in mechanical watchmaking and promote the skill of watchmaking. It features an accessible Chinese-made tourbillion, allowing the wearer to enjoy a complication usually reserved for extremely expensive watches.

The Tourbillion was developed to try and alleviate the issue of gravity affecting the time keeping of pocket watches. Because a pocket watch was stored vertically in pockets or on desk stands, this would mean that gravity would cause the watch to run at a slightly different speed depending on its orientation.

The Tourbillion provided the solution to this by placing the escapement and balance wheel within a tiny cage, which was geared to rotate continuously, completing one 360-degree rotation every 60 seconds. This ‘averaged’ gravity, cancelling the positional errors, resulting in uniform timekeeping.

They are considered such a fine piece of watchmaking because they are very difficult and time consuming to make, thus making them expensive.

The dial is the satin silver tone and has the engine turned finish which catches the eye. To the exterior is the smooth finish for the minute track which has the black dashes with the Arabic numerals for the 5 second graduations. The hour markers are the black roman numerals with the BHI logo sitting below 12 o’clock and the ‘BHI 150’ signing next to three o’clock. The sub-second dial is cut out, allowing you to see the tourbillion. The exterior has the smooth finish which matched the minute track. It has dot markers on the 5 second graduations with dashes for the single graduations. The Flying Tourbillion is the star of the show, rotating 360 degrees every minute. It took us a while to realise it had the sub-second pointer to the tip which indicates the seconds!

The hour and minute hands are of the index style with luminous in-fill to the centre. They have the polished finish which catches the eye. The dial and hands are protected by the mineral crystal which has a subtle bevelled edge.

The case measures 42mm wide without the crown and 46mm wide with the crown. It has a lug-to-lug length of 51mm which a case depth of 11.3mm. The lug width is well sized at 20mm.

It has the polished finish with the circular design. The bezel is gently curved which is a neat surround to the dial. The lugs are a straight design with subtly curved edges and flat sides. The sides of the main body of the case are curved with the pleasing onion style crown to the right-hand side. The case back screws in place and has 6 notches for opening. It is engraved with the specifics of the watch which are well defined. It features the mineral crystal which exposes the movement.

The movement is the Liaoning calibre 5010, which is manually wind with the flying tourbillion. It has a jewel count of 15, operating at a frequency of 21,600 BPH with a power reserve of 50 hours. The service history is unknown, but it continues to keep accurate time to within 20 seconds per day.

The watch is presented on the original leather strap with the BHI stainless steel deployment buckle.

The watch is modelled on a 7” wrist circumference
Full condition report below. Please see the images as these compliment and aid the description provided below.

Dial:
The dial is original and is in very good condition. It has no visible marking.

Hands:
The hands are original and are in good condition with the bright polished finish and luminous.

Glass:
The mineral crystal is in good condition with no obvious marking.

Crown:
The crown is in good condition with only light scratching to the polished face.

Case:
The case is formed of stainless steel with the polished finish. It is in original condition and has light scratching associated with age and wear. The strap bars are screwed in place.

Caseback:
The case back is in good condition with light scratching associated with age. The mineral crystal has no marking.

Strap:
The watch is presented on its original leather strap with the BHI steel clasp. The strap has signs of wear and ageing.

Movement:
The movement is the Liaoning calibre 5010, which is manually wind with the flying tourbillion. The service history is unknown, but it keeps accurate time to within 20 seconds per day, with an amplitude of 225 degrees and a beat error of 0.1m/s.

Case dimensions
Case width: 42mm
Case width with crown: 46mm
Case length: 42mm
Case length lug to lug: 51.1mm
Case depth: 11.3mm
Lug width: 20mm