From the Telegraph of 7 March 2012:
JOHNSON On 6th February 2012, at The Chelsea and Westminster Hospital, to Alice and Dominic, a son, Alexander Charles Andrew.
Dominic Robert Andrew (b 1974 reg June, London) s of Patrick R JOHNSON and Juliet E C HARVEY (later Madame Ivan Brumpt)
Hon Alice Rose Alethea HAMILTON (b 1974) d of the LP Baron HAMILTON OF EPSOM (b 1941 s of 3rd Baron HAMILTON OF DALZELL and his wife a gd of the 2nd Earl of LEICESTER) and Anne Catherine (b 1940, a week after her father’s death) d of Cdr Trevylyan Michael NAPIER DSC RN (1901-ka 1940), scion of that gentry family of Pennard House, of the CULME-SEYMOUR Bts and barons MONSON.
Michael posted news of the parents’ engagement in 2005: https://groups.google.com/forum/?fromgroups#!searchin/peerage-news/dominic$20johnson/peerage-news/JPI_acxeK6k/-fnLSXNVQOMJ
… and news of their marriage & blessing in 2006: https://groups.google.com/forum/?fromgroups#!searchin/peerage-news/dominic$20johnson/peerage-news/dz-BkGlAtUY/6sxaNeoxX3wJ