Let's be honest if you stop and think about it starting a new tax year on the 6th April does seem pretty random really doesn't it! Making it 1st January would seem far more logical save for the fact that back in the Tudor times and the time of the Julian calendar the start of the year was deemed to be 25th March or Lady Day as it was known. Fast forward to 1752 and after 170 years out in the wilderness dear old England decided to finally fall in line with the rest of Europe and adopt the Gregorian calendar. By this time we were 11 days out of sync with our neighbours so the September of that year jumped from 2nd straight to the 14th. Understandably people were up in arms as they were still expected to pay tax for the full 365 days despite the year only having 354. The following year the Treasury shifted the tax date from March to 5th April to ensure it got its full 365 days worth of taxation groats and then it was moved once again to the 6th in 1800 [something to do with leap years under one type of calendar but not the other]. As you will all be too painfully aware there it's stuck.
"Be wary of strong drink. It can make you shoot at tax collectors.....and miss!"
Robert A Heinlein
On that low note I'm off ignore my tax return which will need to be submitted at some point and find something more scintillating to do. Once I've finished watching the paint dry maybe I'll consider it......