Are you certain Mary Alice was actually born in Shrewsbury as there is no birth in that area in 1916 on the GRO index.
If you know her actual date of birth and/or her mothers maiden name, you can look on the GRO index to find her birth reference and then buy a copy of her birth cert. the same goes for Robert
You can now search the full GRO index yourself free of charge at
http://www.ancestry.co.uk/search/rectype/vital/freebmd/bmd.aspx Choose “Complete BMD Index Ranges & Images 1837-1983
If you only have a dial up internet connection and you live in the UK, you may find it easier to view the same index at your nearest main library as the images take a while to download. If you have broadband, they only take a few seconds
The partially transcribed index (freebmd) can also be searched on the same website or at
http://freebmd.rootsweb.comCopy certificates can be obtained online at
www.gro.gov.uk