I want to create a single column LineLegend with at least 12 different entries. Suppose that I define lists colors and names as follows:
colors = {Red, Magenta, Pink, Orange, Yellow, Green, Darker[Green], Cyan, Blue, Purple, Black, Gray}; names = Table["Color " <> ToString[i], {i, 1, Length[colors]}]; If I use colors[[;; 10]] to show only the first 10 entries in LineLegend with LegendLayout -> "Column", I get a nice single column LineLegend:
LineLegend[colors[[;; 10]], names, LegendLayout -> "Column", LabelStyle -> {20, FontFamily -> "Arial"}] 
However, if I show 11 or more entries, the legends become double-columned:
LineLegend[colors[[;; 11]], names, LegendLayout -> "Column", LabelStyle -> {20, FontFamily -> "Arial"}] 
LineLegend[colors, names, LegendLayout -> "Column", LabelStyle -> {20, FontFamily -> "Arial"}] 
How can I force LineLegend to put the legend entries in a single column?

f[pairs_] := Grid[pairs]; LineLegend[colors, names, LegendLayout -> f, LabelStyle -> {20, FontFamily -> "Arial"}]gives !Mathematica graphics $\endgroup$