I had to look up "bolthole." It's "a hole by which to bolt or escape; figurative a means of escape" (OED).
1877 E. Peacock Gloss. Words Manley & Corringham, Lincs. Bolt-hole, (1) the hole by which a rabbit makes its escape when the ferret pursues it. (2) Any unknown hole by which a person makes his way into or out of a house....A very rabbit-y concept.
1924 E. Marsh tr. La Fontaine Fables 71 [The hare] heard a rustle, And took the hint to bustle Off to his bolt-hole.
1932 H. Simpson Boomerang xii. 306 A girl who had been jilted might choose any bolt-hole to hide her shame....
And while I'm here in the OED, let me look up "lockdown" (a word that we're seeing a lot this week and that I suspect will not go away for a long time). The oldest meaning is "a piece of wood used in the construction of rafts when transporting timber downriver." That goes back to the 19th century. The next oldest meaning of "lockdown," dating only to the 1970s, is the prison meaning — keeping prisoners in their cells for a long time (notably after an outbreak of violence). Most recently, going back to 1984, the word came into use to refer to "A state of isolation, containment, or restricted access, usually instituted as a security measure; the imposition of this state." Examples:
1999 Computerworld 11 Oct. 8/1 (heading) Many users plan Y2K lockdowns.I heard NY Governor Andrew Cuomo struggling with the word on this morning's "The Daily" podcast. He said it was a scary word, and he didn't want to use it. It would mean that people are required to stay inside their own homes, and he wanted to assure New Yorkers that he would not do that, yet it was obvious that he was going to say that whether it was true or not, as he openly talked about the problem of causing a destructive stampede to the stores.
2002 Quill (Nexis) 1 May 34 We heard the city was on lockdown and that it wasn't possible to get in.
2005 Courier-Mail (Brisbane) 3 May 3/5 Contestants go into lockdown tomorrow isolated from the outside world as they prepare to enter the Big Brother house on Sunday.