You couldn't really blame Frank Dobson for having a dig at Ken Livingstone.

At the start of yet another week in the long, long campaign to be London mayor, there he was sitting on the platform at yet another mayoral hustings meeting.

Fellow candidates Steve Norris and Susan Kramer were there. An audience of a respectable size had turned up. And there were even two men on the third row dressed up as large blue rats.

But of Mr Livingstone, there was no sign.

The independent candidate in this high profile race was "for some reason or another" unable to attend, we were told somewhat wearily by the chairman.

And Mr Dobson, referring to last week's detailing of Mr Livingstone's earnings from public speaking, couldn't resist a little jibe.

"None of us on the platform are receiving a fee," he said, half-jokingly, half-cynically.

Tricky task

Beyond that, however, it was evening of little discord.

Mr Dobson, Mr Norris and Ms Kramer were addressing the problems of the skills shortages affecting London, with Christian People's Alliance candidate Ram Gidoomal also attending as a late substitute for Mr Livingstone, who was apparently holding a constituency surgery.

But for around 10 minutes at the beginning of the debate, the most tricky task for the candidates was to work out what to do in response to the two comedy rats sitting directly in front of them.

Carrying placards showing disdain for both Mr Dobson and Mr Livingstone, the two men - who said they were ferrets rather than rats, as if it mattered - sat silently, pretending to fall asleep.

It made a slight mockery of the claim from an opening speaker that this was an audience made up of decision makers.

Thrown out

Clearly this was true, but there were also two men dressed up as large blue rats sitting in front of her, whom one would hope have few key decisions in their, er, paws.

They wouldn't say where they had come from or why they were there, but whatever their reasons, their presence certainly provided a surreal touch to the evening.

Just when it seemed as though they planned to stay put for the duration, however, and much to the relief of the four mayoral hopefuls, one rose from his seat to shout praise for Mr Dobson, while the other shouted abuse. Then they were thrown out.

At least, I think that's what happened, but it may have been a dream.

Beyond that, we witnessed a reasoned debate. Too reasoned, in fact.

Indeed, Mr Norris, responding to a question about BMW's decision to sell-off Rover and whether the strength of the pound was a factor, was almost gleeful at finding himself at odds with Ms Kramer.

Nodded away

"At last," he said, with relish: "Something to disagree on."

He had a point. Indeed, up until then, it had been all sweetness and light. "Steve was right on such and such," said Ms Kramer, at one point. "As Susan says", said Mr Dobson, at another.

Mr Norris, meanwhile, nodded away contentedly on numerous occasions as his adversaries spoke. Mr Gidoomal had to rush off early - but not before everyone had pretty much agreed with him and vice-versa.

In fact, when Ms Kramer turned on Mr Dobson ever so slightly at one point - and only once - he even looked a little hurt.

To wind up the evening, we went on to a question about the importance of London to the rest of the country - and, unsurprisingly, everyone agreed with each other again.

It was all enough to make you wonder if they're suffering from hustings burn-out. One way or another, and even taking Mr Livingstone's absence into account, something just wasn't quite right.

And I'm not talking about the surreal comedy rats.