Hi Lyndon,
you've quite possibly seen these websites, but just in case;

http://www.herefordshire.gov.uk/htt/580.aspx and
http://www.midlandspubs.co.uk/breweries/herefordshire/hereford-and-tredegar.htm
which starts,

"The origins of this brewery can be traced back to the late 18th century when Nathaniel Purchas was operating a brewing enterprise in Fownhope. He formed a partnership with Robert Whittesley and, together, they brewed ales and imported spirits that were brought up from Bristol via the Severn Estuary and the River Wye.
Following the death of Nathaniel Purchas in 1817, son William formed a partnership with John and William Reynolds to continue the business. William Purchas later relinquished his interest in the Fownhope Brewery and, in 1834, John Reynolds relocated the business to a new purpose-built site in Hereford's Bewell Street......"

From this site's PRs:

Record_ID: 43141
Entry_Number: 157
Year: 1772
Month: Dec
Day: 17
Grooms_Surname: PURCHAS
Grooms_Forenames: Nathaniel
Grooms_Age:
Groom_Condition: batch[elor]
Grooms_Occupation:
Grooms_Residence: Fownhope (Heref[ord]s[hire]ords)
Grooms_Fathers_Surname:
Grooms_Fathers_Forenames:
Grooms_Fathers_Occupation:
Brides_Surname: WILLIAMS
Brides_Forenames: Martha
Brides_Age:
Brides_Condition: Spin[ster]
Brides_Occupation:
Brides_Residence: o[f] t[his] p[arish]
Brides_Fathers_Surname:
Brides_Fathers_Forenames:
Brides_Fathers_Occupation:
Licence_or_Banns: Licence
Date_of_Banns:
Signature_or_Mark: Both sign
Witness_1: Henry Braban
Witness_2: W[illia]m Perkins
Other_Witnesses:
Officiating_Minister:
Event: Marriage
Memoranda:
Notes: Residence should probably be Fownhope
Register_Reference: 1754-1779
Page_Number:
Parish_Chapel: Chepstow
Soundex_Groom: P622
Soundex_Bride: W452

Record_ID: 339169
Entry_Number:
Year: 1798
Month: Sep
Day: 7
Parents_Surname: PURCHAS
Child_Forenames: Nathaniel
Fathers_Forenames: Thomas
Mothers_Forenames: Sarah
Mothers_Surname:
Residence:
Occupation:
Officiating_Minister: [not stated]
Event: Baptism
Memoranda:
Notes:
Register_Reference: AG39/3
Page_Number: 57
Parish_Chapel: Ross on Wye
Soundex: P622

Record_ID: 239048
Entry_Number: 176
Year: 1816
Month: Jun
Day: 4
Surname: PURCHAS
Forenames: Nathaniel
Residence: of this parish
Age_at_death: 17 yrs
Officiating_Minister: Ja. Mills Curate
Event: Burial
Cause_of_death:
Memoranda:
Notes:
Register_Reference:
Page_No: 22
Parish_Chapel: Ross on Wye
Soundex: P622

Record ID 241643
Entry Number 833
Year 1822
Month Dec
Day 25
Parents Surname PURCHAS
Child Forenames William Henry
Fathers Forenames Thomas Whittlesey
Mothers Forenames Jane
Mothers Surname
Residence in this parish
Occupation Wine Merchant
Officiating Minister Ja[me]s Mills
Event Baptism
Memoranda son of
Notes
Register Reference AG39/4
Page Number 105
Parish Chapel Ross on Wye

Record_ID: 76159
Entry_Number: 311
Year: 1844
Month: Feb
Day: 19
Surname: PURCHASE
Forenames: Nathaniel
Residence: Chase-House
Age_at_death: 69
Officiating_Minister: Frederick Stonhouse Curate
Event: Burial
Cause_of_death:
Memoranda:
Notes: Surname confirmed from Death Register vol 26 page 59
Register_Reference: P175 IN 1/6
Page_No: 39
Parish_Chapel: Hewelsfield
Soundex: P622

Record ID 312165
Entry Number 435
Year 1871
Month Jan
Day 6
Parents Surname PURCHAS
Child Forenames William Bishop
Fathers Forenames Charles Whittlesey
Mothers Forenames Elizabeth
Mothers Surname
Residence Morecambe Lodge
Occupation Wine Merchant
Officiating Minister M R West Curate
Event Baptism
Memoranda Son of
Notes
Register Reference AG39/7
Page Number 55
Parish Chapel Ross on Wye

In 1842 the Hereford Brewery at Fownhope was bought by Charles Watkins, the publican of the Imperial Hotel Widemarsh Street Hereford (still a pub), hence he renamed it the Imperial Brewery. His son Alfred born at the Hotel in 1855 became an accomplished & innovative photographer and the "inventor" of ley lines.
http://en.wikipedia.org/wiki/Alfred_Watkins

C WATKINS PATENT STEAM BREWERY, HEREFORD
http://www.galata.co.uk/assets/uploaded/docs/3.pdf

The following site has an interesting history of Charles's later years in Bewell House Hereford, as told thro' the late 1800s Census's.
http://www.youngand.co.uk/bewell%20house%20history.html

From LDS here is his 1881 Census, I see Charles is a Forester born Mitcheldean !!

"England and Wales Census, 1881,"
name: Charles Watkins
age: 61
gender: Male
birth year: 1820
birthplace: Mitcheldean, Gloucestershire, Wales
relationship to head of household: Head
marital condition: Married
profession/occupation: Brewer Miller Wine Merchant & Farmer Malster Innkeeper & Employ 59 M 16 W & 6 B
address: Bewell House
census place: Hereford All Saints, Herefordshire, Wales
disability:
record type: Household
family history library film: 1341625
the national archives reference: RG11
piece/folio: 2594 / 23
page number: 40
Household Gender Age Birthplace
head Charles Watkins M 61 Mitcheldean, Gloucestershire, Wales
wife Ann Watkins F 60 Huntley, Gloucestershire, Wales
daughter Charlotte Watkins F 33 All Saints, Herefordshire, Wales
son Henry Watkins M 27 All Saints, Herefordshire, Wales
son Alfred Watkins M 26 All Saints, Herefordshire, Wales
servant Sarah Hughes F 58 Wales
servant Mary A Brown F 27 Fownhope, Herefordshire, Wales
servant Emma Evans F 19 Eaton Bishop, Herefordshire, Wales

So from this site's PRs:

Record_ID: 41858
Entry_Number: 173
Year: 1820
Month: Feb
Day: 6
Parents_Surname: WATKINS
Child_Forenames: Charles
Fathers_Forenames: John
Mothers_Forenames: Charlotte
Mothers_Surname:
Residence: Mitchel Dean
Occupation: Farmer
Officiating_Minister: John Newport Curate
Event: Baptism
Memoranda:
Notes:
Register_Reference: P 220 IN 1/3
Page_Number: 22
Parish_Chapel: Mitcheldean
Soundex: W325

"In 1898 the Brewery was acquired by the Tredegar Brewery & renamed the Hereford and Tredegar Brewery Ltd. It remained so until being acquired in 1945 by the Cheltenham Original Brewery Ltd, a company later known as the Cheltenham and Hereford Breweries Ltd."