CALLS for restraint and respect have been made ahead of Baroness Thatcher's funeral on Wednesday as the bishop of the former prime minister's home town suggested its cost and scale were a "mistake" that could play into the hands of extremists.

Tim Ellis, the Bishop of Grantham in Lincolnshire, said the ceremonial event, costing up to £10 million and involving more than 700 armed forces personnel, was "asking for trouble" amid divisions over Baroness Thatcher's legacy.

"In a context where there is manifestly great ill-feeling about her tenure and about her legacy, to then actually have a situation where we seem to be expecting the nation to glorify that with a £10m funeral ... any sensible person would say that that is asking for trouble."

He added: "It plays into the hands of those more extreme people who will use the funeral as an opportunity to promote certain political views."

Earlier, Francis Maude, the Cabinet Office Minister who has been chairing the funeral co-ordination committee, urged people thinking about staging a protest along the route to St Paul's Cathedral to be respectful.

"It's a free country and people must be free to express their views. I would simply ask that they should respect the wishes of the mourners, of which there will be very many, for this event to take place in a dignified and seemly way."

He added: "It's just worth making the point that around the world there are hundreds of millions of people who enjoy freedom and who are able to say what they want to say without fear or favour because of her, because of what she stood up for."

Protesters say they have been given the go-ahead by the Metropolitan Police to turn their backs on the coffin as it makes its way to St Paul's.

David Ison, the Dean of St Paul's, urged those lining the route to remember that the event on Wednesday was about a human being's death.

He stressed Baroness Thatcher was "not some kind of monster or a witch but was actually a human being doing what she believed to be right and we can respect that even though we may not agree with her politics".

After 16 people were arrested following an anti-Thatcher protest party in Trafalgar Square on Saturday night, Scotland Yard warned a similar fate could await any demonstrator, who caused "harassment, alarm or distress" at the funeral.

Today, Downing Street expects to learn whether or not US President Barack Obama will attend the event on Wednesday morning. It is also thought former Presidents George W Bush and his father George HW Bush have been invited.

Meanwhile, more guests were announced. They included: Marco Pierre White, the celebrity chef; Boris Johnson, the London mayor; and Gerald Ronson, the businessman, who was jailed for his part in the Guinness shares scandal.

Sir Frank Williams, the Formula One boss, has accepted an invitation, as have broadcaster Martyn Lewis and Paul Dacre, editor of the Daily Mail.

A raft of military top brass will also be present, including General Sir David Richards, the Chief of the Defence Staff; and General Sir Mike Jackson, the former head of the Army.

In a separate development, plans for a £15m memorial library and museum in London filled with artefacts from Lady Thatcher's time in office have been revealed.

The project – based on the Ronald Reagan Presidential Library and Museum in California – is said to have the backing of at least three current Cabinet ministers as well as key lieutenants of the former prime minister from the 1980s.

Yesterday, a Tory backbencher insisted Lady Thatcher's death had galvanised his party. Conor Burns, who visited her every Sunday night, said: "There is tribal loyalty that has re-entered the Tory soul, which perhaps hasn't been around in recent months.

"David (Cameron) recognises, as we all do, that we are all in her shadow. She is one of the historic greats. She will go down with Elizabeth I, Winston Churchill and Queen Victoria as one of those towering historic figures."