The following are the different time clocks in comparison to the British Summer Time zone, at 3pm BST which is the current usual time of NCF meetings:

Why do time zones exist?

A time zone is a geographical area that follows a consistent standard time for legal, business, and social purposes. Since it is more practical for locations in regular communication to preserve the same time, time zones tend to follow the borders of nations and their subdivisions rather than rigidly following longitude.

All time zones are described as offsets from Coordinated Universal Time (UTC), with offsets ranging from UTC12:00 to UTC+14:00. The offsets are normally a whole number of hours, however some zones, such as India, South Australia, and Nepal, are offset by an additional 30 or 45 minutes.

By around 1900, practically every inhabited region on the planet had adopted a standard time zone, although only a few of them employed an hourly offset from GMT. Many people applied the time at a local astronomical observatory to the whole country, with little regard for GMT. It took decades for all time zones to be established on some sort of uniform offset from GMT or Coordinated Universal Time (UTC).

Though, all countries now utilise standard time zones for secular reasons, although not all of them implement the notion as it was intended. Some nations, such as China and India, utilise a single time zone despite having a territory that much exceeds the optimal 15° of longitude for one hour; others, such as Spain and Argentina, use regular hour-based time zone offsets. In Russia, which has 11 time zones, two time zones were removed in 2010 and reinstated in 2014

How Many Time Zones Exist?

There would be 24 time zones in the world if each time zone was one hour apart. Nevertheless, because some time zones only have 30 and 45 minute offsets, the overall number globally is substantially larger.
Certain higher latitude locations observe daylight saving time for around half of the year, often by adding one hour to local time during the spring and summer.
California, for instance, utilises Pacific Daylight Time (PDT) with a UTC offset of UTC-7 during DST, but Pacific Standard Time (PST) with an offset of UTC-8 the rest of the year.

UTC Offset is used to define this.

Every location on Earth is measured in terms of its distance east or west of Greenwich, London, United Kingdom’s prime meridian (0°longitude). This is also the Coordinated Universal Time (UTC) reference point, with 1 hour per 15 degrees longitude.

British Summer Time (BST) advances civil time in the United Kingdom by one hour relative to Greenwich Mean Time (GMT). This effectively changes the time zone from UTC00:00 to UTC+01:00, resulting in one hour less daylight in the mornings and one hour more in the evenings.

To obtain the proper time zone in hours, divide the longitude in degrees by 15. As an example:

The time should be 150 degrees west (or 150° W) longitude divided by 15 degrees = 10 hours behind UTC, or UTC-10.
At 75 degrees east (or 75 degrees E) longitude, the time is 75 degrees divided by 15 degrees, which equals 5 hours ahead of UTC, or UTC+5.

Conclusion

Each 1-hour time zone is 15 degrees broad in theory, suggesting a 1-hour variation in mean solar time. The white and grey stripes on our Time Zone Map and in the image above represent this.

The actual boundaries on a time zone map are drawn to correlate with both internal and international borders, and seldom exactly line up with the 15-degree time zone borders.

Several geographically big (broad) countries, such as India and China, employ only one time zone, while it would be logical to anticipate many, as in the United States or Australia.