St. Mary's Church, The Parade, Castletown, IM9 1LG
Description
Cowley Groves are delighted to market this approx. 5,430sq/ft unique detached office building for rent in the heart of Castletown centre. Subletting opportunities are available, subject to separate negotiation. St Mary's House is a large detached office building located in the hub of Castletown Square in the south of the Island. The building underwent extensive renovation approximately 10 years ago and the history of the building is said to stretch to over 200 years ago. The property enjoys views of the square and Castle Rushen to the front plus uninterrupted views of the Irish Sea to the rear. The property is set across ground and first floors, serviced by both a lift and two staircases. The ground floor comprises of a large reception and a series of small, medium and larger offices with a breakout/kitchen area - there is also an on-site shower. The first floor is a large open plan office with three smaller private rooms/offices. The property benefits from 18 private car parking spaces and is close to essential amenities for staff members, including coffee shops and convenience stores. The landlord welcomes a FRI lease on the entire building, however the lead tenant may sublet to further occupiers, subject to contract.
A phone number or email address in the agent’s own wording has been removed. This site publishes contact details for nobody — not the agents, not the firms it lists, not its own operator — so that no one gets a direct line on a page that treats them all the same. Their full text, including how to reach them, is on their own listing, linked above.
‹ Back to searchNot marked as sole agency on the original listing, so this property may also be marketed by other agents not captured in this data.
Nearby
- SchoolVictoria Road Primary School0.40 mi · 9 min walk · 1 min drive
- GP surgeryCastletown Medical Centre0.46 mi · 10 min walk · 1 min drive
- DentistPort Erin Dentist (temporary)0.12 mi · 2 min walk · 0 min drive
- SupermarketCo-op Food0.05 mi · 1 min walk · 0 min drive
- PubThe Garrison0.04 mi · 1 min walk · 0 min drive
- RestaurantLeonardo's0.04 mi · 1 min walk · 0 min drive
- CaféJust Jenny's Cakes & Coffee0.07 mi · 2 min walk · 0 min drive
- Petrol stationS & S Motors0.46 mi · 10 min walk · 1 min drive
- AirportIsle of Man Airport1.8 mi · 6 min drive
Nearest match in each category, from a fixed list of Isle of Man amenities — not every pub, café or shop on the island, so treat this as a useful sample, not a complete picture. Distances are straight-line ("as the crow flies"), multiplied by 1.3 to approximate real road-network distance — this is an estimate, not turn-by-turn routing, and actual walking/driving routes may differ. Times assume constant average speeds appropriate to the Isle of Man's roads and 25/35mph limits: walking 4.5 km/h, cycling 14 km/h, driving 30 km/h — not open-road speeds, and they don't account for traffic, parking or terrain.
Masts nearby
- Communication mastUnnamed on the map125 yards away
- Mobile phone mastUnnamed on the map0.59 miles away
- Mobile phone mastUnnamed on the map0.62 miles away
- Communication towerUnnamed on the map1.5 miles away
Read this before drawing a conclusion. These are masts mapped by OpenStreetMap contributors — 38 communication structures for the whole island, 29 of them tagged as carrying a mobile network. The operators run considerably more sites than that, so a mast not shown here is not evidence there isn't one. There is no official Isle of Man mast register to check against: Ofcom's Sitefinder never covered the island and the Communications Commission publishes no list. Nothing in this data says which generation a mast carries, so none of it can tell you whether a site is 5G.
This looks like a registered building
A property matching this listing's name appears on the Isle of Man's Protected Buildings Register, registered on 15 Mar 1984. Registration is a legal constraint, not a label: altering, extending or demolishing a registered building requires Registered Building Consent under the Town and Country Planning Act 1999, in addition to ordinary planning permission, and that applies to work an unregistered house would not need permission for at all.
Matched by building name against the public register, not by a shared identifier — no such identifier exists. Treat it as a strong prompt to check, not as proof: confirm against Planning and Building Control's own register before you offer, and ask your advocate. Equally, nothing here proves a property is NOT registered — see the full register.
What would improving it be worth?
Value added is the extra floor area priced at £2,651/m² — the midpoint asking price per m² among 28 Isle of Man properties currently for sale that publish a floor area. Cost uses real Isle of Man build rates: £4,000–£6,000/m² new build and £2,000–£4,000/m² refurbishment, depending on quality. Net is against the mid rate. The last column is how often Isle of Man actually grants that kind of application.
| Improvement | Value it might add | Likely cost | Net | Granted |
|---|---|---|---|---|
| Add a bedroom (single-storey extension) A modest double plus circulation, built new. ~14 m² |
£37,116 | £52,500 14 m² · mid spec new build range £42,000–£63,000 |
−£15,384 | 0% (314) |
| Loft conversion with a bedroom Works inside an existing roof, so it prices as refurbishment rather than new build — which is why it usually wins. ~20 m² |
£53,023 | £41,000 20 m² · mid spec refurb range £33,000–£50,000 |
+£12,023 | 0% (46) |
| Two-storey extension Roughly 14 m² on each of two floors. ~28 m² |
£74,232 | £105,000 28 m² · mid spec new build range £84,000–£126,000 |
−£30,768 | 0% (66) |
| Garage, annexe or outbuilding Detached space is worth less per m² than main-house floor area. ~18 m² |
£28,632 | £67,500 18 m² · mid spec new build range £54,000–£81,000 |
−£38,868 | 0% (199) |
Two things it cannot see. First, it prices floor area at the local average rate — it doesn't know your plot, your roof, your outlook, or whether an extension is physically possible; nor whether your street has a ceiling price that no amount of extending beats. Second, the rate comes from asking prices of other properties currently for sale, because the Isle of Man's sold register records no floor areas at all — so it reflects what sellers ask, not what buyers paid.
The obvious alternative method is worse, which is why it isn't used here: comparing a typical 3-bed with a typical 4-bed suggests a bedroom is worth around £430,000 island-wide. It isn't — a 4-bed is generally a bigger house on a bigger plot, so that figure measures the mix of what's for sale, not the value of adding a room.
Before spending anything, get a builder's quote and talk to an architect — what work of this kind actually gets approved here shows how often applications like yours succeed, and on what grounds the refusals go.
Building work on this property
Same estimate model this site uses on its planning pages (UK cost ranges with the Isle of Man's 18% uplift) — a rough starting point, not a quote. Always get quotes from an Isle of Man builder before budgeting.
See also all Isle of Man property professionals — architects, surveyors, mortgage brokers and trades.
Sale history
| Sale date | Price | At 2026 prices | Address on register |
|---|---|---|---|
| 2020-03-02 | £1,172,500 | £1,552,050 +32% | St Marys Church Castletown Square Castletown IM9 1LG |
| 2014-02-11 | £1,172,500 | £1,699,136 +45% | St Marys Church Castletown Square Castletown IM9 1LG |
Matched by house name/street and parish against the Isle of Man Land Registry's transaction register — not a unique-ID lookup, so a shared house name could span more than one property. The "2026 prices" column carries each price forward at the island-wide repeat-sales index — it is what that sum of money would be at today's market level, not a valuation of this property, and it takes no account of the condition it was in then or any work done since.
Planning history
No planning application found in this site's planning dataset for this address.
Search the official register for anything since 2023
Latest to rent
