The numerical arrangement of the wonders is a conflation of the 20 wonders found in the fullest lists of the Irish versions of the Historia (See Translations: though note that this list is taken from a collation of manuscripts not a specific manuscript), with the 20 overlapping wonders from the lists of the British versions.

The following table makes explicit the derivation of the ordering. It is notable that there are 20 wonders in each list:

NumberWonderBritish listsIrish lists
1Loch Lumonoy 11
2Trahannon River 22
3The Fiery Pool 33
4The Salt Fountains 44
5Two Severn Kings 55
6Llyn Liuan 6
7Fount Guur Helic 76
8The Appled Ash 87
9The Wind Hole 98
10The Levitating Altar 109
11The Returning Plank 11*
12Cabal's Cairn 12*10
13Amr's Tomb 13*11
14Cruc Mawr Tomb 14*
15Brebic's Stone Cataract12
16Mauchline's Quern 13
17The Well of Bones 14
18The Undersea Birds 15
19The Limpets of Ceoil 16
20The Screams of Glen Ailbe17
21The Sealess Shore 15*18
22The Circling Rock 16*
23The Swelling Shallows 17*19
24The Walking Stone 18*20
25Loch Lein 19*
26Loch Echach 20*

*Missing from Manuscript D, though whether this is true of all Gildasian manuscripts (See Manuscripts) is not obvious.

The British lists are likely to be the earlier ones, as in the Irish versions the text has been edited down considerably. However, the insertion of Irish list numbers 12-17 between the elements found contiguously in the British lists might suggest a fuller initial list of 26, at least for the Irish versions.

British list numbers 1-14, albeit rather disparate, appear to be associated together in a single list in the manuscripts, whereas British list numbers 15-18 are explicitly listed as new list, enumerated from scratch (the connection between these and British list 19 and 20 is ambiguous, but 15-18 are consistently numbered off in the manuscripts, whereas 19 and 20 are not, suggesting a new list).

British list 1-14 cover a wide geographical area centring on the "Old North" of the Scottish borders, Gwent, and the English borderlands. This may suggest collation during a very particular period of British retreat, perhaps re-authored after the lost of the English borderlands to the Saxons (some of the wonders are mentioned as being in the lands of the Saxons).

British list 15-18 are explicitly connected with one region (Mona) and this geographical focus appears to be the case with the Irish lists. This may suggest, along with their position in the manuscripts, that 1-14 represent the oldest core of the lists, and that this core has accumulated newer region-centred lists to it later. However, there is plainly both variation in style in the core list, and a geographical limitation within it to the areas above.

Strangely, the two Irish wonders (British list 19 and 20) don't appear in the Irish manuscripts, though Loch n-Echach does appear in an Irish list associated with the Irish Historia manuscripts: "The Wonders of Eri according to the Book of Glen-Da-Locha" (online).