Many thanks for your kind comments about my explanation, Brooke. Yes, thank goodness that Lady Furnivall seems to be alive and well - and, as you say, we look forward to details of her heirs as these become public knowledge (or, indeed, if any of us discover details that are already public knowledge).
I was also intrigued by Malcolm's comment about peers who succeeded in their nineties and thought I would look up some further information about this for anybody else who might be interested. All the below information is drawn from Leigh Rayment's Peerage Page, which his successor is doing a superb job of maintaining. It appears that Lady Furnivall is one of only five peers (whose dates of birth are known) who succeeded to a title aged at least 90. In descending order of age at succession, they are as follows:
6th Viscount Exmouth - born 26 April 1828, succeeded 16 August 1922 (aged 94 years, 112 days), died 4 February 1923
3rd Baron Parmoor - born 4 July 1885, succeeded 12 May 1977 (aged 91 years, 312 days), died 5 October 1977
11th Countess of Kintore - born 20 September 1874, succeeded 25 May 1966 (aged 91 years, 247 days), died 21 September 1974
6th Baron Churchill - born 11 October 1926, succeeded 17 October 2017 (aged 91 years, 6 days), died 18 October 2020
20th Baroness Furnivall - born 4 April 1935, succeeded 15 October 2025 (aged 90 years, 194 days)
Additionally, I only came across three peers (again, whose dates of birth are known) who were raised to the peerage or had further titles created for them when they were aged at least 90. In descending order of age at creation, they are as follows:
1st and only Baron Maenan - born 9 July 1854, raised to the peerage 23 June 1948 (aged 93 years, 350 days), died 22 September 1951
7th Earl of Longford - born 5 December 1905, created a Life Peer as Baron Pakenham of Cowley 16 November 1999 (aged 93 years, 346 days), died 6 August 2001
1st Earl of Stockton - born 10 February 1894, raised to the peerage 24 February 1984 (aged 90 years, 14 days), died 29 December 1986
Tim