The trains consist of two units, each of 9 coaches. Apart from coach 9, the units are completely identical but facing in opposite directions.
Arrangement of coaches, starting from the London end:
In general seat numbers are two digits ending with 1 to 8:
| Coaches: | 1, 14 to 17 | 2 to 5, 18 | 7 to 9 | 10 to 12 |
|---|---|---|---|---|
| X1, X5 | Left window | Right window | Right window | Left window |
| X2, X6 | Left of aisle | Right of aisle | No such seat | No such seat |
| X3, X7 | Right of aisle | Left of aisle | Left of aisle | Right of aisle |
| X4, X8 | Right window | Left window | Left window | Right window |
("Left" and "Right" are when facing London). Seats X1 to X4 form a row across the coach with identical properties, and seats X5 to X8 another such row. Where tables are provided the seats either side of the table have the same first digit (so in coach 1 seat 25 faces London across a table from seat 21). For each coach the X1 and X5 seats are listed with codes giving details:
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the remaining seats can be derived from these.
| Coach | Seats | End | 11 | 15 | 21 | 25 | 31 | 35 | 41 | 45 | 51 | 55 | 61 | 65 | 71 | 75 | 81 | 85 | End |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 48 | London | EQ | BW | FW | BH | FW | BP | FW | LH | [1] | RH | NH | RH | NW | Europe | |||
| 2 to 5 | 58 | Europe | [2] | LW | LP | LW | LQ | FH | BW | EQ | EW | EH | EQ | EW | EP | EW | EH | London | |
| 7 and 8 | 39 | Europe | FW | BW | LH | LW | FP | BW | EP | EW | EH | FW | BH | FW | BH | London | |||
| 9 | 25 | Europe | [3] | FW | BP | FW | BP | FW | BP | FW | BP | London | |||||||
| 10 | 25 | London | [3] | BW | FP | BW | FP | BW | FP | BW | FP | Europe | |||||||
| 11 and 12 | 39 | London | BW | FW | EH | EW | BP | FW | LP | LW | LH | BW | FH | BW | FH | Europe | |||
| 14 to 17 | 58 | London | [2] | EW | EP | EW | EQ | BH | FW | LQ | LW | LH | LQ | LW | LP | LW | LH | Europe | |
| 18 | 48 | Europe | LQ | FW | BW | FH | BW | FP | BW | EH | [1] | NH | RH | NH | RW | London |
Coaches 6 and 13 are bar coaches. The bar is at the inner end of each coach, on the left as you walk through the coach towards it. The table and stools are on the other side further along the coach.
In coaches 7, 8, 11, and 12 the 1X and 7X blocks are separated from the other seats by a partition.
At London the A, B, and C ramps - used both for boarding and for exit - emerge opposite the doors to coaches 1, 4, and 8 respectively. B is an escalator while the other two are travolators. There is also an exit-only escalator opposite the door to coach 9.
At Paris the exit is at the front of the train. Boarding passengers come down ramps to opposite the doors to coaches 17 and 13.
At Brussels the main exit is also at the front of the train, with a passport check.