Sorry the forum has not been able to give you more specific help with your newly acquired mount...

Here is a model crosstable from the 1981 Bianchi (US) catalogue. There is nothing which corresponds to your example, alas. My guess would be that it may be one model below the Rekord, or perhaps even a Rekord variant. Since you are in the UK it is possible that models distributed there bore some differences to those described in this crosstable.