Reasons to keep my pension and not transfer:
Pension is main source of income in retirement and inflation protection gives me security.
My health, family health is good so I expect to live to normal life expectancy+ and therefore a guaranteed pension for life is good.
I prefer guarantees and guaranteed income, I am not confident with market related investments or pensions that can down or up in value.
My partner has smaller/no pension provision and will need my pension income in retirement as it has a spouses benefit.
I am happy that my pension will cover my financial needs in retirement so there is little point gambling it.