UFO Sightings - 1957 - The English Channel

On April 29th, 1957 an incident happened over the English Channel that was reported, then completely cleared by the RAF.
You decide....

Radar operators picked up two "objects" over the English Channel that as they reported, "aroused their curiosity".
It was so aroused that they launched several RAF Gloster Javelin Interceptors to go check it out.
The Javelin's closed but the targets bolted away from them and pretty much left them sitting.

The official RAF explanation....
They were two brand new Hawker Hunters on training maneuvers.

Problems with that story.....

1. Why were jets in British airspace and the Brits knew nothing about it?
    Maybe they were top secret and it was a covert training exercise?
    Okay....that's possible right?

2. The top speed of a Gloster Javelin is 710 mph.
    The top speed of a Hawker Hunter is 715 mph.
    Five miles an hour is hardly enough of a difference to be able to leave another jet like that in your wake.

3. Ground observers saw two bright metallic objects.
    Okay....still could have been planes with the sun reflecting off them.

4. The radar operations picked up and tracked the two objects on radar for 300 miles before the "jets" hit a burst of speed and disappeared off the scopes, an extra 100 miles, for a total of 400 miles...one way.
    The Hawker Hunter had a 445 mile range. 
    So that meant the two Hunters crashed into the ocean, less than 45 miles out, after outrunning the Javelins.
    Now...the Hunters could carry external fuel tanks that gave them a range of close to 2,000 miles.
    But being weighted down like that should have cut into their "blinding speed".

So what were the Javelins chasing that day that they couldn’t even get close enough to get a visual on?
Experimental aircraft?
Russian fighters that snuck into British airspace?

Or something else?