John Reed (jjreed_3 @t hotmail.com) of St Helens, Lancs says that his granddad Frederick Reed was in the 6th City of London Regiment during the 1914-1918 war. At the time of his marriage in 1915 he was 21, and the certificate records his father, another Frederick Reed, as being a compositor-printer, born at Barnet.

You were able to find Frederick in the 1901 census (born at Barnet) and 1891 census (born at Barnet but transcribed as "Barust") - so I had a look for him in 1881  - as being born anywhere in Hertfordshire - and, using Ancestry, found the following:

1881 census - Gardners Arms, 1 California, Aylesbury, Bucks

If you look at the adjacent pages you will find that a short distance away, in Bourbon Street there was a newspaper printing office, and if you look at the 1883 Buckinghamshire Directory (see Historical Directories) you will find that the paper was the Buckinghamshire Advertiser. This was probably where the Reed brothers worked. This paper, under the name Aylesbury News, was founder in 1836 by my ancestor John Gibbs, and in 1881 the owner and editor was his son, Robert Gibbs, author of The History of Aylesbury, and my great-great-uncle.

I had been hoping to find Frederick at home - to get the name of his parents - but at least the brother gives us an alternative link back to his parents. I had a quick and unsuccessful look for Frederick as being born in Hertfordshire in the 1871 census - but it could be worth your while looking for a Middlesex birth - as the county boundary was very complex at the time.

I have not looked in the 1861 census - and of course Frederick had not been born then - but Arthur had. Instead I went straight to the 1851 census, which I have in printed form (also available on Ancestry). This was to see if there was a Reed family was living in Redbourn shortly before Arthur was born. I found the following family:

1851 Census - High Street, Redbourn (next door to Tom of Bedlam public house)

The first thing to note is that Eliza is much younger than Charles - and was only 12 when Adelaide was born - so it is very likely that she was Charles Reed's second wife. As a Chelsea Pensioner he was a retired soldier - and the fact that two children were born in Ireland could indicate that he was billeted there at the time - with another posting in Berkshire - possibly at Windsor Castle.

More relevantly, as two of Arthur's children were called Charles and Adelaide this looks very promising, (see The Inheritance of Single Christian Names) but it is not enough, on its own, to prove that Charles and Eliza were Frederick's parents. 

What you will need to do is to look for members of the family in the 1861 and 1871 censuses - and also to get relevant birth and marriage certificates to fill in the gaps. See the Tutorial for how to do this. If Charles turns out to be your ancestor you may well be able to chase up his army records in the Public Records Office.

There are web pages for Redbourn & Barnet