After the credit crunch many UK lenders are quite risk averse, and generally the best uk commercial mortgage loans are offered by the more risky lenders who are willing to talk more risk for less return.
The high street banks are some of the most risk adverse lenders; even though you may have banked with them a long time they still may be unwilling to grant large mortgage loans. Self Cert lending and lenders that used to lend without accounts are all but gone now as values of commercial property in the UK still remain uncertain. Commercial mortgage loans in the region of 50% loan to value can still be achieved when the borrower has good accounts over many years.
Lenders may be more willing to lend if a legal charge is taken against the whole business and/or the homes of the directors with the addition of a personal guarantee from the directors. Unfortunately the best UK commercial mortgage loans were back in 2006 when commercial property was viewed in a much different way.