The map below shows isochrones or lines linking places with the same times of sunrise (green lines) and sunset (red lines) for the United Kingdom for mid-December. These lines show the position of the terminator, the boundary between the illuminated and dark areas of the Earth, as it sweeps across the face of the globe. South-east Kent has the earliest sunrise and the Isle of Lewis in the Outer Hebrides has the latest sunrise. The earliest sunset takes place in the Shetland Isles and the latest sunset takes place in the Isles of Scilly. The time system used in the map is Greenwich Mean Time (GMT) which can be regarded as UTC for the purposes of this exercise. For example, we can see that sunrise in Norwich occurs at approximately 08:00 GMT and sunset in Southampton occurs at 16:00 GMT.

If the United Kingdom elected to move to Central European time (CET), one hour in advance of GMT for the Autumn and Winter months, this would mean darker mornings and lighter evenings. For example, sunrise in London would take place at 08:59 CET and sunset would take place at 16:52 CET. In Glasgow, sunrise would take place 09:41 CET and sunset at 16:43 CET. In the case of Northern Ireland, sunrise times would occur between 09:35 CET and 09:50 CET. Stornoway would see the Sun rise at 10:07 CET and set at 16:34 CET.
| Sunrise/set times for mid-December | |||||
| United Kingdom Location | GMT | CET | |||
| Sunrise | Sunset | Sunrise | Sunset | ||
| Lerwick | 09:03 | 14:56 | 10:03 | 15:56 | |
| Kirkwall | 08:59 | 15:14 | 09:59 | 16:14 | |
| Stornoway | 09:07 | 15:34 | 10:07 | 16:34 | |
| Inverness | 08:52 | 15:32 | 09:52 | 16:32 | |
| Aberdeen | 08:41 | 15:25 | 09:41 | 16:25 | |
| Edinburgh | 08:37 | 15:38 | 09:37 | 16:38 | |
| Glasgow | 08:41 | 15:43 | 09:41 | 16:43 | |
| Londonderry | 08:48 | 16:01 | 09:48 | 17:01 | |
| Newcastle | 08:25 | 15:38 | 09:25 | 16:38 | |
| Carlisle | 08:29 | 15:44 | 09:29 | 16:44 | |
| Belfast | 08:39 | 15:58 | 09:39 | 16:58 | |
| Douglas IoM | 08:31 | 15:55 | 09:31 | 16:55 | |
| Leeds | 08:18 | 15:45 | 09:18 | 16:45 | |
| Hull | 08:12 | 15:40 | 09:12 | 16:40 | |
| Manchester | 08:18 | 15:49 | 09:18 | 16:49 | |
| Liverpool | 08:21 | 15:52 | 09:21 | 16:52 | |
| Leicester | 08:09 | 15:49 | 09:09 | 16:49 | |
| Norwich | 07:59 | 15:40 | 08:59 | 16:40 | |
| Birmingham | 08:11 | 15:53 | 09:11 | 16:53 | |
| Aberystwyth | 08:20 | 16:03 | 09:20 | 17:03 | |
| Ipswich | 07:57 | 15:43 | 08:57 | 16:43 | |
| Cardiff | 08:12 | 16:04 | 09:12 | 17:04 | |
| London | 07:59 | 15:52 | 08:59 | 16:52 | |
| Dover | 07:52 | 15:48 | 08:52 | 16:48 | |
| Southampton | 08:02 | 16:00 | 09:02 | 17:00 | |
| Exeter | 08:09 | 16:09 | 09:09 | 17:09 | |
| Penzance | 08:14 | 16:20 | 09:14 | 17:20 | |
| St. Helier | 07:56 | 16:10 | 08:56 | 17:10 | |