[probable] A mechanical expanding drainage test/sealing plug, marked "HOROBIN," installed in a drainage pipe. [unknown] Its exact product name, intended application and maker are not verified.

• EX. 01

• Confirmed

  Material

  Pressed zinc-plated or galvanised steel disc face with a central brass or steel threaded spindle and cross-pin (tommy bar), seated inside an orange/terracotta plastic drainage pipe.

• Confirmed

  Manufacturing method

  Stamped sheet metal circular plate with embossed peripheral lettering and a machined central compression bolt mechanism.

• Confirmed

  Construction & Mechanism

  Mechanical expansion plug (drain stopper). Tightening the central spindle compresses a rubber ring behind the metal plate, expanding it radially against the pipe wall to create an airtight/watertight seal.

• Confirmed

  Context & Setting

  Installed inside an orange underground pipe within a rough concrete, brick, or masonry inspection chamber / rodding point.

• Probable

  Dimensions

  Appears to be standard UK domestic drainage size, typically 4 inches (100 mm / 110 mm outer diameter pipe).

• Confirmed

  Wear & Condition

  Splattered with soil, water marks, and drain residue; light surface oxidisation and staining present on the metalwork.

• Confirmed

  Likely function

  Used for air/water pressure testing of pipework, sealing an unused branch, or capping a drainage rodding access point.

• Confirmed

  Text — Embossed along the left rim of the circular metal plate

  Reads: "HOROBIN"

• Possible

  Text — Possible reading: faint lettering below 'HOROBIN' along the bottom-left c

  Possible reading: "MADE IN ENGLAND"

• Possible

  Text — Possible reading: partially obscured size stampings on the right rim of t

  Possible reading: "100mm / 4 INCH"

• Horobin mechanical drain test plug for nominal 100 mm / 4-inch UK drainage pipe

  82%

  Supports

  • No retrieved sources are available to test or strengthen this hypothesis.
  • The prior score is retained because no new evidence was supplied.

  Argues against

  • No source evidence confirms Horobin, the mechanical drain-test function, or the nominal 100 mm / 4-inch size.

  Would confirm: A sharp photograph of the full face and reverse side showing size, part number, patent number, or other stamped markings; or a directly matching Horobin product catalogue/listing.

• Horobin mechanical access-cap or rodding-point sealing plug

  65%

  Supports

  • No retrieved sources are available to test or strengthen this hypothesis.
  • The prior score is retained because no new evidence was supplied.

  Argues against

  • No source evidence confirms that the object was intended for an access cap or rodding point rather than pipe testing.

  Would confirm: A matching Horobin technical sheet or product marking identifying the item as an access, rodding-point, or branch-sealing plug.

• Horobin mechanical air-test plug used during drainage installation or inspection

  61%

  Supports

  • No retrieved sources are available to test or strengthen this hypothesis.
  • The prior score is retained because no new evidence was supplied.

  Argues against

  • No source evidence confirms an air-test function, installation use, or inspection use.

  Would confirm: Photographic evidence of a test port or a matching manufacturer instruction sheet specifying air/water pressure testing for the same design.

• Generic UK mechanical expanding drain plug, with Horobin as distributor, installer, or component marking rather than confirmed manufacturer

  28%

  Supports

  • No retrieved sources are available to test or strengthen this hypothesis.
  • This remains a possible explanation where a Horobin marking cannot be tied to manufacturing evidence.

  Argues against

  • No source evidence establishes Horobin as a distributor, installer, or component supplier rather than manufacturer.

  Would confirm: A directly sourced period or current trade catalogue that identifies the plug’s actual manufacturer separately from Horobin.

• Older British-made Horobin drain plug, possibly marked "MADE IN ENGLAND"

  24%

  Supports

  • No retrieved sources are available to test or strengthen this hypothesis.
  • Possible reading: "MADE IN ENGLAND" cannot be treated as confirmed without clear object evidence.

  Argues against

  • No source evidence confirms age, British manufacture, Horobin manufacture, or the wording "MADE IN ENGLAND".

  Would confirm: Confirmed legible wording "MADE IN ENGLAND" plus an independently matching Horobin catalogue, patent, or dated trade reference.

— – —

No reliable, supplied market evidence or verified comparable sales were located for this specific Horobin-marked mechanical drain plug.

Rarity 2/10 — Probable standard trade plumbing/drainage hardware rather than a scarce collectible. The visible Horobin marking may help identification, but manufacturer attribution is not confirmed and no production data or market evidence was supplied. Rarity rating concerns availability, not value.

Observed-sale comparables: none supplied or verified; no auction or marketplace sale is claimed. Retail asking prices are not treated as realised values and none were supplied. Object identification is probable rather than confirmed: it appears consistent with a UK mechanical expanding drainage test/access plug, possibly for nominal 100 mm / 4-inch pipe. Condition appears used, with soil, drainage residue, staining and light oxidation; working condition, rubber-seal condition, completeness beyond the visible spindle/cross-pin, exact size, maker attribution and provenance are unknown. Demand is likely functional and trade-led rather than collector-led. Value could vary substantially if the plug is complete, operational and correctly sized, but we couldn't verify a defensible price range.

This is research, not a formal valuation, appraisal or authentication.

• No external sources were supplied, so no maker history, date, catalogue reference, provenance, auction result, market comparison or quotation is claimed.
• The initial wording treated the drainage-test function as confirmed. It has been downgraded to probable where it depends on interpreting the object’s use; only the reported compression-seal mechanism is treated as confirmed.
• The visible "HOROBIN" reading is retained as a case-file observation, but attribution of manufacture to Horobin has been withheld.
• Possible rim text "MADE IN ENGLAND" and "100mm / 4 INCH" was not used as evidence because the reading is uncertain.
• The UK find location and apparent installation style do not prove UK manufacture, so origin is presented only as contextual probability.
• No valuation range is given because no verified realised-sale comparables or defensible pricing evidence were supplied.
• The confidence score of 82 applies only to the broad mechanical expanding drainage-plug identification, not to exact size, maker, date or original use.