I posted on this topic on 17 December 2012.For convenience my post is reproduced below:
"On the 15th December the 8th Duke of Wellington recorded a milestone-he became the longest living Duke in the history of the peerage.The previous holder of that distinction was the 7th Duke of Grafton who died in 1918(great great great grandfather of the present Duke).
There have been 9 Dukes who have lived to the age of 90 or older:-
8th Duke of Wellington 97y5m15d
7th Duke of Grafton 97y5m12d
9th Duke of Portland 93y
8th Duke of Portland 92y
11th Duke of Grafton 92y
HRH 1st Duke of Connaught 91y
HRH the Duke of Edinburgh 91y
9th Duke of Norfolk 90y
8th Duke of Leinster 90y
Note that at the end of February,the Duke of Edinburgh and the Duke of Connaught will swap places and the Duke will become the oldest ever living male in the Royal Family.
Other miscellany:-
The 8th Duke of Wellington is the oldest ever male member of the Order of the Garter,the previous holder of that title being the Earl of Longford.
No Marquess has reached the age of 100-the oldest was the 16th Marquess of Winchester who died age 99.
There have been centenarians in the other grades of the peerage-details can be found at Leigh Rayments peerage page."
Since then the following things have happened:
The 8th Duke of Wellington celebrated his 99th birthday on 2 July.If he is still alive on 1 March 2015 he will become the eldest ever marquess surpassing the 16th Marquess of Winchester,in his capacity as Marquess of Wellington that title being created in 1812
The Duke of Edinburgh celebrated his 93rd birthday on 10 June and is now the oldest ever living male member of the Royal Family(but not of Queen Victoria's male descendants which is the late Count Carl Bernadotte who died in 2012 aged 93 years 6months 5 days,a record the Duke of Edinburgh will surpass on 16 December 2014)