Many broadcast news bulletins featured footage of lorries queuing for miles along the M20 in Kent yesterday (Monday) after France closed its border with the UK.

But Boris Johnson gave a televised briefing putting what appeared to be a positive gloss on events and stressing that the government and local authorities had contingency plans in place.

The prime minister said: “We’ve activated our long-prepared plans, with the result that we’ve already been able to reduce the number of lorries waiting on the M20 from 500 to 170.”

Mr Johnson was speaking just before ten past five on Monday afternoon. He didn’t give any indication that he had an earlier time in mind when he talked about the number of lorries falling.

Exactly one hour before the briefing, Channel 4 News’s Global Trade Correspondent Paul McNamara was told by a senior official from Kent County Council’s Highways department that there were “nearer 500” lorries involved in Operation Stack – the procedure where lorries are parked along the M20 at times of severe congestion at Dover.

Other reporters, including ITV News’s Business and Economics Editor Joel Hills, tweeted that Kent Highways officials had also given him a figure of 500 and that local sources were “baffled” at the much lower number the prime minister gave.

The ITV News reporter added that officials estimated number of lorries queuing on the motorway rose sharply later on Monday – to more than 900 by around 8pm.

This chimes with footage filmed by Channel 4 News’s team in Kent at around the same time. Paul McNamara tweeted this video of nose-to-tail queues on the M20 eastbound, where lorries had formed two lines and no other traffic was flowing.

Although it wasn’t possible to count every individual vehicle from their moving vehicle, the Channel 4 News crew filmed five miles of queues, which equates to 400 to 800 lorries at a conservative estimate.

Unfortunately, bad weather meant there were no news helicopters filming the tailback from above on Monday, but choppers were out on Tuesday morning.

Footage filmed by Sky at 9.20am on Tuesday captures the whole queue of lorries. FactCheck is not able to post the footage here for copyright reasons, but we managed to count 580 lorries still lined up on the M20 on Tuesday morning. (Sky News have used snippets of the aerial footage in their bulletins today).

All of this makes it hard to see how the figure the prime minister gave the nation in his news conference could possibly have been accurate.

It was immediately disputed by local officials, and later footage shows the number of vehicles on the M20 appeared to rise through Monday evening.

And it’s absolutely clear from aerial footage that there were more than 500 lorries still queuing near Dover on Tuesday morning, despite the prime minister’s claim that government plans meant the numbers were falling.

Downing Street has been contacted for comment.