As the owner of PMC's and Harbeth's I would say this.
As with other companies, different lines of speaker differ in voicing. The OB1 and other models of that generation, most of which sat on low stands, likely sounded different and closer to classic BBC profile. I haven't heard one. I own Twenty.24 speakers. I auditioned the Fact line at the same time, and didn't like them as much, although they were more expensive. To me they were leaner and cooler, perhaps more neutral. Then came the TwentyFive series (or however they write it) and my understanding is that that line is voiced closer to the Facts. So as with Spendor, if you want the classic sound you probably want to go back a few years.
As with other companies, different lines of speaker differ in voicing. The OB1 and other models of that generation, most of which sat on low stands, likely sounded different and closer to classic BBC profile. I haven't heard one. I own Twenty.24 speakers. I auditioned the Fact line at the same time, and didn't like them as much, although they were more expensive. To me they were leaner and cooler, perhaps more neutral. Then came the TwentyFive series (or however they write it) and my understanding is that that line is voiced closer to the Facts. So as with Spendor, if you want the classic sound you probably want to go back a few years.