Plutocrat, if you have not heard of 2d I suspect you may have gone astray in that corner. 1d parses 3,4,1 and 'close to Surrey' is not geographical, if that helps? Definition is the last word. 16d is a digit containing 2 for appreciation and 3 for 'fifty-one's', definition 'in sum'
Freddycat, 20 and 23 are both renowned users of the theme, in quite different styles