Sorry for the delay in replying.
There will be a forfeiture clause in the Lease entitled the landlord to forfeit (ie. terminate) the lease in the event of certain things happening, including non-payment of rent and other breaches of covenant. Check the lease for this clause, it will likely be towards the end of the lease. It will be negligent of the landlord's solicitor to have not included this clause. If it is not there then he cannot effect eviction unless he gets a court order and he would have to apply for this and you would receive notice.
If there is a forfeiture clause then the landlord does not technically need to serve notice - they can simply effect forfeiture by re-entering the premises and changing the locks. If this is what has happened then you will not be able to re-enter the premises because the lease is no longer effective and does not give you a right to occupy any longer.
The landlord may get bailiffs to do the above for him.
Alternatively, the landlord can apply to court for an order for eviction, for this he would require notice to be served upon you. This does not sound as if this is the way forward that he has chosen.
Check your lease for the forfeiture clause, but it will probably be there and therefore he has acted within his rights.
Also call your original solicitor to check that the landlord is empowered under the specific terms of the lease.
Sorry it could not be better news, but I'm afraid that this is the nature of commercial property.
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