There are extra ways of getting information from FamilySearch which will help. First, click on the source call number - this links to the Family History Library catalogue and in this case tells you that the record comes from Patron Submitted Sheets, not from controlled extraction. So what you are looking at is an index to entries for a particular family, probably by a member of the LDS Church who searched through the register or looked at an index. Next, try an IGI search using the batch number 8612730. If you include surname Eyre, you get a series of christenings in Great Chalfield with the same parents as Robert, including a Margaret on 24 Jan 1649 - so it is unlikely that Robert was 1 year old and available for baptism in 1649, but not baptised until 1652. To look more at what else is included in the IGI batch of christenings, just search on the batch number without a surname - you get baptisms all over the country and for different surnames, confirming that it is not a systematic extract of Great Chalfield baptisms. To check the series of baptisms you can look at the microfilm of the parish register - film no 1279348 in the Salt Lake City library, and you can obtain a copy at any Family History Centre. Great Chalfield baptisms in general are not indexed in the IGI, but they are in the British Isles Vital Records Index, and the White Horse Index. (see GENUKI Wiltshire via www.genuki.org.uk for information about these). Either of these will give an index independent of the one used by the LDS member who submitted the entries you found. Finally, you are quite right that baptisms and their recording was severely disrupted in the Commonwealth period. Great Chalfield seems to have a continuous set of registers, other parishes have gaps, so the baptism of the Robert Eyre you are interested in may be lost. Other records like wills, burials after the commonwealth period, etc can help you confirm that you have found the correct parish. I hope this helps you, and other people poking around in FamilySearch, regards, David Hawgood