Lesson Sharing - Sale with and without Tenancy

Thought I'll share this recent incident.
A landlord recently sold his condominium, which he claims he had instructed the agent to sell with tenancy. The tenancy had 12 more months to go. The condo was eventually sold but with the "sold subject to an existing Tenancy Agreement" deleted. The new owner insisted on taking vacant possession and the tenant refused to vacate.
When the tenant finally agreed to relocate, the current owner (the landlord) had to give hefty compensation and made a number of concessions. He is also seeking compensation from the agent.