Online Bike Road Tax?

I was intending to have a ride out on Sunday - June 1st.

The bike was SORN'd in May. As the tax ran out at the end of April and I wasn't going to have any opportunity to ride it, so rather than pay for a month road tax, I put it on SORN. I did this over the Internet and printed the receipt.

To use the bike on Sunday June 1st I needed to tax the bike to make it legal, How? The post office seemed keen on selling me a disc that would start on May 1st, even though it was the 31st already.

I checked online, entered the number off the log book plus the reg number and again I was offered tax from the 1st May. I gave up and sent them an email to say it was ridiculous in this instance that you can't renew online for the Sunday as the starting date. Not had a reply yet.

On Sunday morning I logged on again and lo and behold the date had changed to June 1st. SO I renewed. Okay it costs a few quid for them to run the service and whilst it might seem a rip off considering you are paying the Government, it was worth.

Sadly it was drizzling and miserable and I didn't go out anyway!

A question? What is the legality of riding with an out of date tax disc BUT having the receipt to say you had paid in your pocket? Luckily I won't have to test it to find out, as the disc should arrive in the post before I will use the bike at the weekend!