This character appears to be quite willing to part with money if it keeps him up with the latest fad or designer accessory.
We find later on in the play that Mr Birling believes he is due for a knighthood. Generally, most people would be just happy if they were in this position, but he actually finds it as important because it would guarantee his social position.
'I have an idea that your Mother - Lady Croft - while she doesn't object to my girl feels you might have done better for yourself socially.'
Gerald's parents are upper class aristocracy and in that social circle, it is all in a name. The aristocracy hold a title which is inherited and the only other way to receive one, is to be given it by the government or monarchy. Thus Mr Birling finds the knighthood important, as it is a title. A title to say, 'if the government can accept me, surely you can too.' He has the money, the wife, the expectant son-in-law but the knighthood would be the icing on the cake. He means that when he becomes a 'Sir' Birling, he would be one of them and Gerald's
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