IN A post-modern culture, tradition and continuity are a gift. At a time when culture seems to be changing fast, to be able to be located in a tradition that has been passed down for 2000 years gives a real sense of "weight" - a much needed anchor point in the world.

Part of the process of carrying a tradition forward is struggling with it, and engaging in its debates as to how its enquiries can be carried forward. This is what Greenbelt is all about. To keep reforming Christian tradition in a prophetic spirit is to be faithful. To deny it is to disallow that subversive and dangerous memory of Jesus.

Grace is an alternative-worship community in Ealing, a congregation of St Mary's Church, and has been going for more than a decade. Alternative worship likes to work with the traditions and liturgies of the Church, often in creative and playful ways. Communion by Numbers re-presents the eucharist in the context of a meal, which is, of course, where it started, at the Last Supper. Tables are set out in a café style, and groups of six to eight people gather round each table. Music is playing, and the service takes place at the tables.

On each table is a series of numbered envelopes. When a bell rings, someone at the table opens the first envelope, and follows the instructions contained in it. This is repeated, so that progress is made through the numbered envelopes in order. The envelopes correspond to the main elements of a communion service: preparation, thanksgiving, confession, the word, prayer, sharing the Peace, preparing the table, eucharistic prayer, sharing bread and wine, thanksgiving, and blessing.

This may mean, for example, that the word is a Bible passage that is read at the table and then discussed; sharing the Peace could be done by a toast with the glasses round the table; the eucharistic prayer could be prayed, and then bread and wine shared at the tables; the blessing could be accompanied by passing round hot towels from a curry house, and so on.

One of the playful elements in the service is a "text confession", where people are invited to text a confession on their mobile phone to a given number. An automated service sends some words of absolution in reply.

When Grace first held this service, the absolutions experienced a delay. Rather than appearing immediately, they arrived during the eucharistic prayer. Phones started to bleep, and displayed the words "You are forgiven." It was perfect timing.

Preserving tradition is done by driving to the heart of it to understand its significance, and then by doing our best to represent it in our own context. In this sense, Communion by Numbers is traditional worship: it takes the tradition seriously, re-examining the sharing of bread and wine among friends gathered around a table, and reframes it in a contemporary context. The next time someone attends communion at their own church, the experience of Communion by Numbers may well reinvest communion with meaning for them in new and different ways.