This banner mission takes you to all three of the famous museums in South Kensington - Natural History Museum, Science Museum and Victoria and Albert (V&A) Museum, in that order. The whole banner starts and ends in South Kensington Underground Station.
You might want to leave plenty of time to do this banner, as the queues to the museums can get very long, especially during weekends and holidays.
Note that in mission 13, you have to go in both Science Museum, as well as V&A for the last portal.
Several portals are inside small squares that close at dusk, although they are reachable from outside, it would be quicker to go through the squares than to walk around, so better do the banner before dusk.
As mentioned missions 29 and 30 have some portals in Wellington Barracks, but they are not too far in from the front gate and should be reachable with a little GPS drift. All the other portals should be 24/7.
Quick series from Westminster to Embankment, but you don't have to do it that way - I did the series in reverse order and encountered no problem (after this I did the North Bank Wonder banner, which bought me back to where I started. You could also do the North Bank Wonder first then this).
Some portals in Mission 6 are in the Whitehall Garden which closes at night, but they should all be accessible from the road outside.
Quick wander along the north bank of the River Thames, starting from Westminster Station and ending a little bit north to Embankment.
I would not say this is 24/7 - Mission 3 has portals in the Whitehall Gardens and Mission 6 in the Victoria Embankment Gardens:
- Both gardens close at night
- The 3rd portal in Mission 3 (Whitehall Court) is very difficult to reach from the outside of the garden.
- Some portals in Mission 6 are difficult to reach from the road right by the river (south to the garden), but may be accessible from Savoy Place (north to the garden), although I have not tested this personally.
Nice route, roughly in the order of Victoria Station -> Westminster -> Victoria -> Belgravia -> Victoria -> Pimlico -> Victoria. So if you can't finish the mosaic in one go, there are several opportunities to go back to Victoria Station.
As with other mosaics in Hyde Park, this is not 24/7 since Hyde Park closes in the evening. In particular, the last waypoint in mission 9 is in the middle of the Diana, Princess of Wales Memorial Fountain, which closes before Hyde Park does - closing time is 16:00 for Nov. to Feb., 18:00 for Mar. and Oct., and 20:00 for Apr. to Aug. (BTW the Fountain's opening time is 10:00 all year round).
Other than that the mission route is fairly well designed. Although the portals can be hacked in any order, it's best to follow the provided order to avoid backtracking.
(The URL of this page used to point to the C.P. Broersepark Banner Mission, which had a duplicate at here. To remove redundancy, this URL has been freed up, so the new mosaic took the old URL. The previous comment is referring to the C.P. Broersepark Banner Mission.)