〜たが最後: meaning and usage

How to form it

• verb (ta-form)+が最後
• verb (ta-form)+ら+最後

How it is used

Once A happens, B is bound to follow and can't be undone or stopped; B is usually bad. Speech often says 「〜たら最後」. Much stronger than a plain 「〜たら」.

Examples

1. みつかったが最後、真珠は取り上げられてしまうぞ。

   Once the pearl is found, it will be taken away.

2. この本は、読み始めたが最後、読み終わるまでやめられない。

   Once you start this book, you can't put it down until you've finished it.

3. 父は一度話し始めたら最後、二時間は止まらない。

   Once my father starts talking, he won't stop for two hours.

About the example 1. Once A occurs, B inevitably follows (usually an undesirable result that cannot be stopped or continues thereafter)