Yes, the 1830 marriage does give Christopher's surname as Welsh.
Mary Ann (nee Clement) was not dead when some of you have quoted so I think some of you have found the other Christopher (Walsh/Welsh). There was another one around in Liverpool at the same time but I think he moved from there.
Mary Ann is very much alive and kicking in 1841 and 1851 where the family lived at Hurst Street, Liverpool.
By 1861 and 1871 the name Elizabeth is quoted as Head of Family. There seems to be an anomaly and I wondered whether the census-taker had written down wrong information because Elizabeth's age is more like her mother's, Mary Ann's and nothing like the daughter Elizabeth's age. I thought that, perhaps, the census-taker had not written Mary Ann's name down and had managed to give Elizabeth's name as head of family in error. Perhaps Elizabeth was there or not - I can not be sure whether she has died or married.