See the GenUki page for Alderney.
https://www.genuki.org.uk/big/CHI/ALDNote that Alderney is part of the Bailiwick of Guernsey and so much of the Guernsey page is relevant.
Church records
The Church of St Anne (Anglican): Baptisms 1662-1902 with annotations copied from an earlier (missing) book commenced in 1628. 1902 to present day in Church only. Deaths from drowning and Burials 1652 to 1863. Succeeding Registers lost during the Occupation.
Catholic Church of St Anne & St Mary Magdalene: Baptisms March 1849-Oct 1952. Deaths January 1859 to April 1940 and two entries in 1946. Marriages from February 1852 to July 1924.
The Priaulx Library, in Guernsey, have photocopies of Baptisms 1822-1832, Private Baptisms 1819-1821. Burials 1809-1812, 1853-59. Marriages 1841-1886 .
Civil Registration
Births, Deaths from 1850, Marriages from 1886
Try Alderney Court Office
https://courtofalderney.gg/article/159869/Searching-the-RegistersContact details for all enquiries:
Postal Address: Court Office, Queen Elizabeth II Street, Alderney GY9 3TB
Email Address:
Court@Alderney.gov.ggTelephone number: +44 (0)1481 820050