It was "nonsense" for the campaign to keep Scotland in the United Kingdom not to use more English politicians in its early days, a veteran Liberal Democrat said.
Baroness Williams claimed she had had the impression she was "toxic" to the pro-UK campaign.
She added that the Better Together cross party group should "try and demonstrate in practice what they are talking about in words".
Baroness Williams spoke out as she addressed an audience at a referendum campaign event at St Andrews University.
She said: "There was a strong view in the early part of the campaign that it wasn't helpful to have people from England, however close their relations with Scotland might be, come up here.
"I began to get the impression I was so toxic if anybody saw me they would rush out and spray me with insecticide."
She added: "I thought that was nonsense, actually it seems to me if you were going to have a Better Together campaign you should demonstrate togetherness."
The Liberal Democrat, who described herself as a "citizen of the UK with a special affection for Scotland", continued: "I think it's a lesson to Better Together frankly to try and demonstrate in practice what they are talking about in words."
She also told the audience that England could have regional devolution within a decade of more powers being transferred to Holyrood.
Labour, the Conservatives and the Liberal Democrats have all laid out plans for further devolution in the event of a No vote in September's indepedence referendum."
Baroness Williams said: "My belief is that within 10 years of Scotland having greater devolution, I think we will see some moves towards regional devolution in England.
"The reason that I believe very strongly that we need that is because to put it bluntly London has got much too big a share of cake altogether."
She described the UK capital as being like a "huge vacuum cleaner sucking out resources" and added: "Probably the time has come that that process should at least be slowed up."