when Peter rings up Harriet’s flat for the first time in Gaudy Night, how did he get her phone number?
Harriet has just been abroad for 18 months. Peter knows she is back because she’s been mentioned in the Times*. She has recently returned to a new flat, and a new telephone number. I think we can assume that the new number is not in the phone book on the grounds that even if she weren’t ex-directory**, which I’d expect her to be given that if she can’t avoid nasty letters from strangers she doesn’t want nasty phone calls as well, there hasn’t been time for the number to enter a new book in the few weeks in which she’s been in London again.
A quick search of the internet has not been especially fruitful, but the Daily Mail tells me that directory enquiries started with the first telephone service, so that would have been an option, except that Peter doesn’t know Harriet’s new address (she tells him that she has moved flat in answer to his comment that she has a new phone number), and if the books were being used we’re back to the original problem of her not being in them.
So how did he get the number so quickly? Would the operator have sufficient local knowledge to put him through to Miss Vane, newly living in a Bloomsbury flat at an unknown address? Has he phoned the host of the literary party, or got Sally Hardy to do so? Has he phoned Harriet's agent with an excuse, or is that too embarrassing? As Parker lives round the corner, has he got him to make an official enquiry?
I am assuming that he didn’t in fact see her at Ascot, have her trailed home, and only waited for the paper to give him an excuse for knowing she was back, or got whatever border agency there was at the time to report...
*As Bunter’s duties including reading the paper and picking out notable articles, one can only imagine what he was thinking as he marked that particular column in black ink.
**Assuming that to be an option at the time.