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-September. 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. At this time of the year the terminator for both sunrise and sunset runs north south. The coast of East Anglia has the earliest sunrise and sunset and southern part of the Outer Hebrides has the latest sunrise and sunset. The time system used in the map is British Summer Time (BST) which can be regarded as UTC plus one hour for the purposes of this exercise. For example, we can see that sunrise in Inverness occurs at approximately 06:45 BST and sunset in Carlisle occurs at 19:30 BST.

If the United Kingdom elected to move to Central European Summer time (CEST), two hours in advance of UTC for the Spring and Summer months, this would mean darker mornings and lighter evenings. For example, sunrise in London would take place at 07:35 CEST and sunset would take place at 20:16 CEST. In Glasgow, sunrise would take place 07:48 CEST and sunset at 20:36 CEST. In the case of Northern Ireland, sunrise times would occur between 07:50 CEST and 08:05 CEST. Stornoway would see the Sun rise at 07:54 CEST and set at 20:46 CEST.
| Sunrise/set times for mid-September | |||||
| United Kingdom Location | BST | CEST | |||
| Sunrise | Sunset | Sunrise | Sunset | ||
| Lerwick | 06:31 | 19:27 | 07:31 | 20:27 | |
| Kirkwall | 06:39 | 19:34 | 07:39 | 20:34 | |
| Stornoway | 06:54 | 19:46 | 07:54 | 20:46 | |
| Inverness | 06:46 | 19:37 | 07:46 | 20:37 | |
| Aberdeen | 06:38 | 19:28 | 07:38 | 20:28 | |
| Edinburgh | 06:43 | 19:32 | 07:43 | 20:32 | |
| Glasgow | 06:48 | 19:36 | 07:48 | 20:36 | |
| Londonderry | 07:01 | 19:47 | 08:01 | 20:47 | |
| Newcastle | 06:38 | 19:25 | 07:38 | 20:25 | |
| Carlisle | 06:43 | 19:30 | 07:43 | 20:30 | |
| Belfast | 06:55 | 19:42 | 07:55 | 20:42 | |
| Douglas IoM | 06:50 | 19:35 | 07:50 | 20:35 | |
| Leeds | 06:39 | 19:24 | 07:39 | 20:24 | |
| Hull | 06:34 | 19:19 | 07:34 | 20:19 | |
| Manchester | 06:42 | 19:26 | 07:42 | 20:26 | |
| Liverpool | 06:44 | 19:29 | 07:44 | 20:29 | |
| Leicester | 06:37 | 19:21 | 07:37 | 20:21 | |
| Norwich | 06:28 | 19:11 | 07:28 | 20:11 | |
| Birmingham | 06:41 | 19:24 | 07:41 | 20:24 | |
| Aberystwyth | 06:50 | 19:33 | 07:50 | 20:33 | |
| Ipswich | 06:29 | 19:11 | 07:29 | 20:11 | |
| Cardiff | 06:47 | 19:29 | 07:47 | 20:29 | |
| London | 06:35 | 19:16 | 07:35 | 20:16 | |
| Dover | 06:29 | 19:10 | 07:29 | 20:10 | |
| Southampton | 06:40 | 19:21 | 07:40 | 20:21 | |
| Exeter | 06:49 | 19:29 | 07:49 | 20:29 | |
| Penzance | 06:57 | 19:37 | 07:57 | 20:37 | |
| St. Helier | 06:44 | 19:23 | 07:44 | 20:23 | |