Martello update

13 August 2026

Richmond Hill Resources Plc

(“ Richmond Hill ” or the “ Company ”)

Martello update

High grade assays at Sakoose and New Church Lake

Richmond Hill Resources plc ("Richmond Hill" or the "Company") is pleased to announce the results from its recent field programme and the acquisition of 16 single cell mining claims.

Highlights

Surface Exploration — Sakoose Mine Area

The Company's first surface sampling programme at the Sakoose Mine has confirmed high-grade gold mineralisation within the historic workings. Metallic screen fire assay results include:

  •   25.9g/t Au from an outcrop between two historic stope shafts (C2920220)

  •   16.2g/t Au from inside Shaft 2 (C2920224)

Surface Exploration — New Church Lake Discovery

A new high-grade gold target has been identified at the New Church Lake occurrence, located within the Martello property. Metallic screen fire assay results include:

  •   23.3g/t Au with visible gold (C2920204)

  •   7.53g/t Au (C2920205) from stockpile material at the same structure.

Fourteen additional samples collected at New Church Lake returned values below 0.25g/t Au, indicating that gold mineralisation is associated with the identified shear structure rather than broadly distributed. New Church Lake represents a potential new mineralised centre on the Martello property, distinct from the Sakoose system. The Company is evaluating follow-up channel sampling and drill targeting at this occurrence.

Diamond Drill Programme

The Company confirms that it expects to commence its maiden diamond drill programme at the Sakoose Mine in Q4 2026. The programme comprises approximately 1,400 metres in nine holes from five pad locations, designed to:

  •   Confirm historic high-grade intercepts using modern QA/QC protocols;

  •   Test the down-plunge extension of the principal high-grade shoot below the historic workings,

  •   Test beneath the main historic underground workings.

  •   Test the eastern extension and a structural intersection.

Claims acquisition

Richmond Hill recently acquired 16 single cell mining claims (totalling c.330 hectares) for a nominal amount from two individual vendors (see Figure 3 in the appendix).   These claims importantly add land which is near a past producing mine (Tabor) and very close to a highly prospective target (New Church Lake).

Hamish Harris, Executive Director commented: “ Our first surface programme at Sakoose has confirmed high-grade gold at a historic mine that produced at a reported grade of approximately 16 g/tAu. A sample collected from outcrop between two historic stope shafts returned 25.9 g/t Au by metallic screen fire assay. This result is supported by multiple sampling programmes returning grades exceeding 10g/t Au within the Sakoose mine area. The next step is to test the system at depth.

“Our nine-hole programme has been designed to target the interpreted down-plunge extensions of Sakoose’s strongest historic drill intersections, using modern geological targeting and modern QA/QC and assay protocols. Drilling is fully permitted, with mobilisation planned for Q4 2026.

At New Church Lake, visible gold was observed in a bedrock sample that returned 23.3g/t Au from a structure associated with historic workings. This strengthens New Church Lake as a target within the Martello portfolio and supports its ranking in the recent 3D magnetic interpretation. We now have two confirmed high-grade gold occurrences warranting systematic exploration, and I look forward to updating shareholders as work progresses. ”

QUALIFIED PERSON

The technical information contained in this announcement has been reviewed and approved by Sheldon Modeland, P.Geo., a director of the Company and a current member of the Association of Professional Engineers and Geoscientists of Saskatchewan (APEGS). Mr. Modeland acts as the Qualified Person for the purposes of the AIM Rules for Companies - Note for Mining and Oil & Gas Companies.

Richmond Hill Resources Hamish Harris	Tel: [phone]
Cairn Financial Advisers LLP (Nominated Adviser) Ludovico Lazzaretti / James Western	Tel: [phone]
Clear Capital Limited (Broker) Bob Roberts	Tel: [phone]

Further information on the Company can be found on its website at www.richmondhillresources.com

Caution regarding forward looking statements

Certain statements in this announcement, are, or may be deemed to be, forward looking statements. Forward looking statements are identified by their use of terms and phrases such as ''believe'', ''could'', "should" ''envisage'', ''estimate'', ''intend'', ''may'', ''plan'', ''potentially'', "expect", ''will'' or the negative of those, variations or comparable expressions, including references to assumptions. These forward looking statements are not based on historical facts but rather on the Directors' current expectations and assumptions regarding the Company's future growth, results of operations, performance, future capital and other expenditures (including the amount, nature and sources of funding thereof), competitive advantages, business prospects and opportunities. Such forward looking statements reflect the Directors' current beliefs and assumptions and are based on information currently available to the Directors.

Appendix

Surface Programme — Full Results

A total of 32 rock samples (plus 1 certified reference material, 2 blanks, and 1 field duplicate) were collected during the July 2026 field programme across three target areas. All samples were collected by Critical Discoveries Inc., and submitted to for gold analysis.

Table 1. Sakoose Mine Area (11 samples)

Sample ID	Sample type	Au (g/t)	Coarse fraction Au (g/t)	Description
C2920220	Outcrop (in-situ)	25.9	240	Between stope shafts, QFP host, 15 cm vein, 080°/31°
C2920224	In-shaft	16.2	132	Inside Shaft 2, 35–40 cm smoky Qz vein, 077°/65°
C2920223	Shaft wall	4.36	—	Shaft 2 exterior wall, ~4 m from C2920224
C2920219	Stockpile	1.80	—	Stockpile material at open stope
C2920226	Chip (outcrop)	1.60	—	Quartz-vein waste material
C2920228	Chip (outcrop)	1.15	—	NE zone, silicified QFP and quartz vein
C2920222	Stockpile	0.95	—	Basalt, stockpile at historic sample location
C2920227	Chip (outcrop)	0.58	—	NE zone, wider vein exposure
C2920225	Grab	0.38	—	Silicified QFP near shaft area
C2920219	Grab	0.04	—	Near shaft area
C2920218	Grab	0.02	—	Silicified QFP near shaft area

Table 2. New Church Lake (16 samples)

Sample ID	Sample type	Au (g/t)	Coarse fraction Au (g/t)	Description
C2920204	Outcrop (in-situ)	23.3	218	3.5 cm Qz-VG-FeOx vein in 0.9–1.0 m shear, gabbro, 170°/52°
C2920205	Stockpile	7.53	52.2	Stockpile at same structure
C2920209	Stockpile	0.248	—	Quartz-vein stockpile, ~25 m north of high-grade zone
C2920214	Outcrop	0.116	—	Oxidised Qz-Po-Py vein in gabbro, 120°/39°, ~600 m NNW
C2920196–215	Various	<0.10	—	12 additional samples, all below 0.10 g/t Au

Copeland (5 samples)

Five samples from the Copeland occurrence returned a maximum of 0.057 g/t Au. The Company notes the identification of quartz-feldspar porphyry at the Copeland shaft, a lithology associated with gold mineralisation at the Sakoose and Tabor Lake deposits. Surface gold values at Copeland remain sub-economic.

Firgure 1. New Church Lake assay results (2026 in larger font)

Figure 2. Sakoose assay results (2026 in larger font)

Figure 3. Updated claim map

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