Short answer — the clearest Scottish‑heritage boutique hotel in Colombo is The Steuart (aka The Steuart by Citrus), which occupies the old Steuart House (headquarters of George Steuart & Co., a firm founded by the Steuart brothers from Scotland) and is deliberately styled with Scottish-themed rooms and a Scottish pub. (citrusleisure.com, steuartstea.com)

Other heritage/boutique hotels in Colombo (colonial-era character, but not explicitly Scottish):

• Galle Face Hotel — iconic 19th‑century beachfront heritage hotel (British colonial era). (en.wikipedia.org)
• Grand Oriental Hotel (GOH) — a long‑standing heritage hotel in the Fort area (late 19th century). (en.wikipedia.org)
• Maniumpathy — an intimate boutique heritage house in Cinnamon Gardens, restored as a colonial‑style boutique hotel. (maniumpathy.com, guide.michelin.com)

If you want, I can give addresses, contact details, room examples, or current rates/availability for any of these (I can look those up now).