Hi,
I see you've been onboard for a few years, are you linked to forum member Sophie Williams who was researching the Longhope Constances a few years back (and who I now remember I need to contact !...) ?. Hopefully you've seen and maybe contributed-to her Constance threads in the past eg
http://forest-of-dean.net/fodmembers/index.php?mode=thread&id=43233

Off the top of my head I cannot recall how far back these threads went. However browsing this site's Parish Records I can see several possible ancestors of yours in the 1700s and earlier, from all across the Forest, have you seen them ?. As well as the Littledean ones you mention see also at nearby Flaxley & Abenhall and maybe Westbury too. Don't forget to tick the Soundex box when searching, there are several spelt "Constants" and "Constans" and such like, and especially look-out for Huntley P.R.s as they seem to go back a little further than the Longhope ones, and are only a couple of miles away.
http://www.forest-of-dean.net/joomla/index.php/forest-of-dean-parish-map

Using the great "advanced search" feature you can look-up all Baptisms, for example, by inputing just "Consta" into parent's surname, and "Huntley" for Chapel.
http://forest-of-dean.net/joomla/index.php/advanced-search
You can then sort the results by clicking on the relevant column heading, to give this list of PRs which look like two generations;

Year.Surname. Child Forenames. Fathers & Mothers Forenames.Parish Chapel.

1756 CONSTANCE Richard. Richard & Isabel. Huntley
1759 CONSTANCE Anne. Richard & Isabel. Huntley
1760 CONSTANCE Anne. Richard & Isabel. Huntley

1780 CONSTANCE Ann. [not stated] Ann. Huntley
1785 CONSTANT Mary. Rich[ar]d & Hannah. Huntley
1787 CONSTANT John. Rich[ar]d & Hannah. Huntley
1789 CONSTANT Sarah. Rich[ar]d & Hannah.Huntley
1794 CONSTANCE Richard. Richard & Hannah. Huntley
1797 CONSTANT Nancy. Rich[ar]d & Hannah. Huntley

Looking for them and other "old" CONSTANCES in the 1841 Longhope Census gives this, not sure if one or more households as can only use FamilySearch site at this time;

1841 Longhope, Longhope Lower, Gloucestershire, England.
Household Role Sex Age Birthplace
Benjamin Constance M 65-69 Gloucestershire
Ann Constance F 66-70 Gloucestershire
Henry Constance M 30-34 Gloucestershire
Richard Constance M 25-29 Gloucestershire
Phoebe Constance F 25-29 Gloucestershire
Eliza Constance F 25-29
Thomas Clulee M 50-54
Caroline Williams F 30-34 Gloucestershire
Caroline Williams F 12 Gloucestershire
Thomas Valender M 35-39 Gloucestershire

1841 The Walk, Longhope Lower, Gloucestershire, England.
Household Role Sex Age Birthplace
John Constance M 60-64 Gloucestershire
Hannah Constance F 60-64 Gloucestershire
Amos Constance M 20-24 Gloucestershire

1841 Chestgrove, Longhope Lower, Gloucestershire, England.
Household Role Sex Age Birthplace
Theophilus Constance M 75-79 Gloucestershire
Mary Constance F 75-79 Gloucestershire

1841 Yew Tree Inn, Longhope Lower, Gloucestershire, England.
Household Role Sex Age Birthplace
Thomas Constance M 58-62 Gloucestershire
Mary Constance F 55-59 Gloucestershire
Hannah Constance F 25-29 Gloucestershire
Benjamin Constance M 20-24 Gloucestershire
Eli Constance M 15-19 Gloucestershire

Of these examples Theophilus is the oldest, and I suspect has been covered in past threads and your research, looks to me like he's from Newent area so not far from Longhope, possibly this line ?.

Record_ID: 24249
Entry_Number: 442
Year: 1724
Month: Jan
Day: 28
Grooms_Surname: CONSTANT
Grooms_Forenames: John
Grooms_Age:
Groom_Condition:
Grooms_Occupation:
Grooms_Residence: Newent
Grooms_Fathers_Surname:
Grooms_Fathers_Forenames:
Grooms_Fathers_Occupation:
Brides_Surname: DRINKWATER
Brides_Forenames: Mary
Brides_Age:
Brides_Condition:
Brides_Occupation:
Brides_Residence: Churcham
Brides_Fathers_Surname:
Brides_Fathers_Forenames:
Brides_Fathers_Occupation:
Licence_or_Banns:
Date_of_Banns:
Signature_or_Mark:
Witness_1:
Witness_2:
Other_Witnesses:
Officiating_Minister: Mr Thomas Avenant vicar
Event: Marriage
Memoranda: Old style date 1723/4
Notes: Ayl Parsons Arthur Hope churchwardens
Register_Reference: P225 IN 1/2
Page_Number: 98
Parish_Chapel: Newent
Soundex_Groom: C523
Soundex_Bride: D652

Record_ID: 260618
Entry_Number:
Year: 1760
Month: Oct
Day: 14
Parents_Surname: CONSTANT
Child_Forenames: Theophilus
Fathers_Forenames: John
Mothers_Forenames: Mary
Mothers_Surname:
Residence:
Occupation:
Officiating_Minister:
Event: Baptism
Memoranda: son of
Notes:
Register_Reference: P332 IN 1/1
Page_Number: 30
Parish_Chapel: Tibberton
Soundex: C523

Record_ID: 64025
Entry_Number:
Year: 1788
Month: Sep
Day: 1
Grooms_Surname: CONSTANT
Grooms_Forenames: Theophilus
Grooms_Age:
Groom_Condition: Bachelor
Grooms_Occupation:
Grooms_Residence: of the Parish of Longhope
Grooms_Fathers_Surname:
Grooms_Fathers_Forenames:
Grooms_Fathers_Occupation:
Brides_Surname: DAWES
Brides_Forenames: Mary
Brides_Age:
Brides_Condition: Spinster
Brides_Occupation:
Brides_Residence: of this parish
Brides_Fathers_Surname:
Brides_Fathers_Forenames:
Brides_Fathers_Occupation:
Licence_or_Banns: Licence
Date_of_Banns:
Signature_or_Mark: Both sign
Witness_1: Richard Terrett
Witness_2: John Greenwood
Other_Witnesses:
Officiating_Minister: John Copner
Event: Marriage
Memoranda:
Notes:
Register_Reference: P138 IN 1/6
Page_Number: 53
Parish_Chapel: English Bicknor
Soundex_Groom: C523
Soundex_Bride: D200

Unfortunately the excellent Longhope Village site doesn't include the 1841 Census info in it's Family History section.
http://www.longhopevillage.co.uk/FamilyHistory/

It appears that the Constance family may not have been in Longhope much before the 1700s, see http://www.longhopevillage.co.uk/FamilyHistory/Parish/Index.aspx

Hoping this helps in some way,
Jeff.

Having a quick look at the Gloucestershire Genealogical Database

from 1500 to 1600

Seaching by CONSTANCE

WILLS

1544 COWSTANS - Roger (Westbury on Severn)
1570 CONSTANCE - Thomas (Westbury on Severn) Husbandman
1576 COWSTANCE - Philip (Stanway) - Labourer
1589 COSTANCE - Richard (Flaxley) - Butcher
1591 CONSTNS - John (Westbury on Severn) Weaver

Will have a look at these Wills which should be on Ancestry (could be in Latin/early English - difficult sometimes to read!!

Transcriptions on the Forest of Dean Records

Flaxley - baptisms

Anne CONSTANS - 1567
Robert CONSTANS - 1567

Use the Soundex on the Record Search (quite a few COWSTAN/COWSTANCE or even COUSTANS/CUSTANES etc)

See later reply: i.e baptism 1726 of Elizabeth CONSTANT alias COWSTANT at Newent