Hi Julia,
my grandparents were tenant landlords at a Forest pub for 25+ years so I have an interest in beer beyond the obvious ! Records re pubs and inns vary enormously, I suggest contacting the Boat itself would be a good start as they may well have records.
http://www.theboatpenallt.co.uk/aboutus.html

Even if they don't know about past landlords they may know whether the pub was tied to a particular brewery or not within a particular timeframe. My guess is it's more likely your ancestors were tenants rather than owners, but that is just my guess.

Normally the great Easywell website is THE place to look, often this lists past landlords, I think gleaned from the various Trade Directories.
HOWEVER and most unusually the entry for the Boat is very small with no history info at all!
http://www.gloucestershirepubs.co.uk/AllGlosPubsDatabase/AllGlosPubs_view.php
(suggest search "Redbrook" to minimise the hits to page thro, cannot do direct links)

The above site's owner/author Geoff Sandles has just released a book abt FoD pubs, I'm sure the Boat will be mentioned due to it's unusual & scenic location, try looking it up in the library perhaps if you live locally. His earlier book about Glostershire Pubs offers very minimal coverage of the FoD, it's only reference to Redbrook is wrt "the Redbrook Brewery founded 1825 by Oliver Arthur Burgham and sold to Ind Coope of Burton on Trent in 1923 along with twentytwo local pubs", the Boat is not one of those named, so....??. The brewery photo shows a building that looks larger/different to me than the Boat Inn itself.
http://www.geograph.org.uk/photo/289413
http://www.forest-of-dean.net/gallery/fod_variety_2/pages/page_5.html

My other usually very helpfull book abt Forest Pubs by Heather Hurley has much detail abt the Redbrook pubs but, again, virtually nothing abt the Boat !. However it does say that at its industrial height Redbrook was known to have "consisted largely of inns !", perhaps an exaggeration for mid C19th Redbrook..
It also says the Redbrook brwery was founded by Richard Sims, then sold to James Hall until his death in 1844. It was eventually sold as a "genteel residence and commodious malthouse" to Thomas Burgham (see Burgham webpage below). There was another local brewery in Upper Redbrook operated by the Ansleys, flour mill owners.
This book states that The Boat Inn was supplied by "Ind Coope & Allsopp Burton Ales in 1939". So it seems like a probable source of info re your ancestors would be the Ind Coope archives which I guess are at Burton Upon Trent.

Next place to look would be the local Trade Directories, although this will usually only tell you when a person kept a pub, rather than who owned it. Please see
http://www.forum.forest-of-dean.net/index.php?id=35123

Please can you advise how you know your ancestors were at the Boat, do you have Census records that show this, or ?. I cannot find Caleb in a quick look at this site's PRs, I'm asking to find out when they were at the Boat ??.

From Ancestry free search page(sorry no full subscription)

"England & Wales, FreeBMD Birth Index, 1837-1915"
Name: Caleb George Brown
Date of Registration: Oct-Nov-Dec 1877
Registration district: Monmouth

And dies 1917 as you say.
So sadly my suggestion of Trade Directories may be less practical as the more recent C20th ones usually are not free to access.

I see but cannot read his entry in the 1891 Wales Census, is this where the Boat is mentioned ?. This seems (to me) to be the nearest "fit" for the couple in the free to view 1911 Census, but this George is described as a Tinworker(like much of Redbrook) albeit living in Penalt (ie the Boat Inn part of Redbrook)

1911 Wales Census, Birches Penalt.

George Brown Head abt 1878 33 Male Married 11yrs Tinworker-Boxer Parkend Glo'shire England
Mary Brown Wife abt 1878 33 Female Married 11 yrs Llandogo Monmouthshire Wales
Willie Brown Son abt 1901 10 Male School Redbrook Monmouthshire Wales
Albert Brown Son abt 1905 6 Male Redbrook Monmouthshire

http://interactive.ancestry.co.uk/2353/RG14_31766_0157_06/407683?backurl=http%3a%2f%2fs...

Hope this helps a little,
Jeff

ps altho abt a different family, this webpage may be of interest re C19th Redbrook and the Brewery.
http://www.burgumfamily.com/pages/pl%20redbrook.html

The Boat Inn has quite a history, look to their web page which records as follows:-

"The pub has been owned by the Jelf family for over 350 years; here is a little bit of their history.

Legend has it that when King Charles II was fleeing from his enemies after the battle of Worcester in 1651 a royal subject called Jelf ferried him to freedom across the River Severn at Ashleworth. In gratitude, the monarch granted to Jelf and his descendents the right to Ashleworth ferry crossing alongside their old farmhouse-turned-inn. However, other records suggest that these privileges may have been given to the Jelfs even earlier, by Prince Edward of March (later King Edward IV) when we was fleeing from his enemies of the House of Lancaster in about 1460. Certainly the family was in the village at a time when one John Jelfes was identified as an Ashleworth leaseholder in 1450. Six of his male descendents were listed as being military age in 1522.

The pub was passed down from father to son until the early twentieth century when sisters Irene and Sybil Jelf inherited it. They ran it together for over 25 years until the death of Sybil in 1990. Irene then ran it partnership with her niece Jaqueline Nicholls. Jaqueline was passionate about Real Ale and worked hard to create a reputation for serving good beer, wining numerous CAMRA awards@...(worth contacting the current landlords - and is worth a visit).

There are numerous accounts of the Jelf family of Ashleworth who managed the inn, the ferry, fishing rights along the Severn (look to British History on-line for anecdotes)

Kind Regards

Bailey