You've worked it out wrong, there's almost no difference between the daily death rate in Italy and the UK, since the first respective death was reported in each country (it hasn't yet actually been twenty days since our first death).
First Italian No First UK
23/02/2020 1 05/03/2020 1
24/02/2020 2 06/03/2020 2
25/02/2020 3 07/03/2020 2
26/02/2020 7 08/03/2020 3
27/02/2020 11 09/03/2020 3
28/02/2020 12 10/03/2020 6
29/02/2020 17 11/03/2020 8
01/03/2020 21 12/03/2020 10
02/03/2020 29 13/03/2020 11
03/03/2020 41 14/03/2020 21
04/03/2020 79 15/03/2020 35
05/03/2020 107 16/03/2020 55
06/03/2020 148 17/03/2020 71
07/03/2020 197 18/03/2020 104
08/03/2020 233 19/03/2020 144
09/03/2020 366 20/03/2020 177
10/03/2020 463 21/03/2020 233
11/03/2020 631 22/03/2020 281
12/03/2020 827 23/03/2020 309
13/03/2020 1016 24/03/2020 335