Not an expert but this is what I've found:
Question: what is the difference in an uk mia 54923 and a uk mia imp 54923
UK MIA 54923 refers to a Manufacturer's Authorisation for the manufacture of medicinal products, while UK MIA(IMP) 54923 specifically pertains to the authorisation for the manufacture and importation of Investigational Medicinal Products (IMPs). The latter includes additional regulations and oversight related to clinical trials.
Authorisation Holder
Both authorisations can be held by the same entity, such as Advent BioServices Ltd, but they serve different regulatory purposes.
Conclusion
The main difference lies in the specific focus of the UK MIA(IMP) on investigational products used in clinical trials, while the UK MIA covers a broader range of medicinal products.
Todays update removes part 2 or Part 2 - IMPORTATION OF MEDICINAL PRODUCTS.
Todays updates states: 6: Legal Basis of authorisation Regulation 17 of The Human Medicines Regulations 2012 (SI
2012/1916)
Where as previously it was: 6: Legal Basis of authorisation Part 6 of The Medicines for Human Use (Clinical Trials)
Regulations 2004 [SI 2004/1031]