Hello, I am a solicitor with 20 years experience. I will try to answer this.
Unless there is something specific in you lease then the new landlord is not entitled to payment for anything that the previous landlord agreed to allow without payment. However if a dispute arises you may have difficulty proving that you were given permission by the previous freeholder.
Look to your lease. Are there any provisions relating to payments for allowing alterations. I not they would need to be able to demonstrate that they had suffered loss in order to claim compensation. They may find this difficult.