Complex sentence: After his death, he was succeeded in his titles by his son the Hon Ernest Illingworth Holden (born in 1867), who became the 3rd baronet Holden and the 2nd Baron Holden.
Split into simpler sentences: After his death he was succeded by his son the Hon Ernest Illingworth Holden who was born in 1867. The Hon Ernest Illingworth Holden was 3rd baronet Holden and then became 2nd Baron Holden.