from fastapi import APIRouter, HTTPException
from pydantic import BaseModel
from typing import List

router = APIRouter()

# Model
class Book(BaseModel):
    id: int
    title: str
    author: str
    pages: int

# Database (in-memory storage)
books: List[Book] = []

@router.post("/books", status_code=201)
async def create_book(book: Book):
    """Create a new book"""
    if request.method != "POST":
        raise HTTPException(status_code=405, detail="Method Not Allowed")

    book.id = len(books) + 1
    books.append(book)

    return {
        "message": "Book created successfully",
        "book": book,
        "method": "POST",
        "_verb": "post"
    }
```

This code defines a `Book` model using Pydantic's `BaseModel`, and an in-memory `books` list to store the book data. The `@router.post("/books")` endpoint accepts a `Book` object in the request body, assigns it a new `id`, appends it to the `books` list, and returns a success response with the created book object and metadata about the HTTP method used.

The code also includes a check for the HTTP method, raising a `405 Method Not Allowed` exception if the request method is not `POST`. The response includes the `"method": "POST"` and `"_verb": "post"` fields as required.

Note that this is a basic example, and in a real-world application, you would likely use a database instead of an in-memory list, and implement additional features such as data validation, error handling, and authentication/authorization.