Hello,
We had to deal with a similar situation about a year ago, with Vodafone shares. A couple of phonecalls, coupled with completion of a fairly straight forward document they sent out and copy of the Will was all that was needed. Granted, the shareholding was relatively modest (sub €500) but that should not really matter, other than perhaps for the additional requirement of wanting a solicitor rather than just one of the executors to complete the documentation.
There were no charges and the new share cert was issued in a matter of 3-4 weeks as I recall.
As Brendan says, call the Registrar, they should be able to assist and I'd suspect there will be no charge.